lvmreport

title: lvmreport(7)

summary: LVM reporting and related features

text:
# lvmreport(7)

## NAME
lvmreport — LVM reporting and related features

## DESCRIPTION
LVM uses single reporting infrastructure that sets standard on LVM command's output and it provides wide range of configuration settings and command line options to customize report and filter the report's output.

## USAGE

### Categorization based on reporting facility
Based on functionality, commands which make use of the reporting infrastructure are divided in two groups:

Report-oriented commands

These commands inform about current LVM state and their primary role is to display this information in compendious way. To make a distinction, we will name this report as main report. The set of report-only commands include: pvs, vgs, lvs, pvdisplay, vgdisplay, lvdisplay, lvm devtypes, lvm fullreport. For further information about main report, see Main report specifics.

Processing-oriented commands

These commands are responsible for changing LVM state and they do not contain any main report as identified for report-oriented commands, they only perform some kind of processing. The set of processing-oriented commands includes: pvcreate, vgcreate, lvcreate, pvchange, vgchange, lvchange, pvremove, vgremove, lvremove, pvresize, vgextend, vgreduce, lvextend, lvreduce, lvresize, lvrename, pvscan, vgscan, lvscan, pvmove, vgcfgbackup, vgck, vgconvert, vgexport, vgimport, vgmknodes.

If enabled, so called log report is either displayed solely (for processing-oriented commands) or in addition to main report (for report-oriented commands). The log report contains a log of operations, messages and per-object status with complete object identification collected during LVM command execution. See Log report specifics for more information about this report type.

### Terms
When describing reporting functionality and features in this text, we will use terms row and column. By row we mean series of values reported for single entity (for example single PV, VG or LV). Each value from the row then belongs to a column of certain type. The columns have column headings which are short descriptions for the columns. The columns are referenced by column names. Please note that this text is also using term field interchangeably with the term column. Most of the time the term columns is abbreviated as col in configuration.

### Common report configuration settings and command line options
There are common configuration settings and command line options which apply to both main report and log report. Following lists contain all of them, separated into groups based on their use.

### Common configuration settings
Changing report output format, composition and other output modifiers:

- global/suffix

- global/units

- report/aligned

- report/binary_values_as_numeric

- report/columns_as_rows

- report/compact_output

- report/compact_output_cols

- report/headings

- report/list_item_separator

- report/mark_hidden_devices

- report/output_format

- report/prefixes

- report/quoted

- report/separator

- report/time_format

- report/two_word_unknown_device

Special settings

- report/buffered

This document does not describe these settings in more detail - if you need detailed information, including values which are accepted for the settings, please run lvmconfig --type default --withcomments <setting>. There are more configuration settings in addition to the common set listed above, but they are specific to either main report or log report, see main report specifics and log report specifics for these settings. Besides configuring reports globally by using configuration settings, there are also command line options you can use to extend, override or further specify the report configuration.

### Common command line options
Definition of the set of fields to use

-o|--options FieldSet

Field set to use. See main report specifics and log report specifics for information about field sets configured with global configuration settings that this option overrides.

-o|--options +FieldSet

Fields to include to current field set. See main report specifics and log report specifics for information about field sets configured with global configuration settings that this option extends.

-o|--options -FieldSet

Fields to exclude from current field set. See main report specifics and log report specifics for information about field sets configured with global configuration settings that this option reduces.

-o|--options #FieldSet

Compaction of unused fields. Overrides report/compact_output_cols configuration setting.

Sorting

-O|--sort +FieldSet

Fields to sort by in ascending order. See main report specifics and log report specifics for information about field sets configured with global configuration settings that this option overrides.

-O|--sort -FieldSet

Fields to sort by in descending order. See main report specifics and log report specifics for information about fields sets configured with global configuration settings that this options overrides.

Selection

-S|--select Selection

Define selection criteria for report output. For log report, this also overrides log/command_log_selection configuration setting, see also log report specifics.

Changing output format and composition

--reportformat

Overrides report/output_format configuration setting.

--aligned

Overrides report/aligned configuration setting.

--binary

Overrides report/binary_values_as_numeric configuration setting.

--nameprefixes

Overrides report/prefixes configuration setting.

--noheadings

Overrides report/noheadings configuration setting.

--nosuffix

Overrides global/suffix configuration setting.

--rows

Overrides report/columns_as_rows configuration setting.

--separator

Overrides report/separator configuration setting.

--units

Overrides global/units configuration setting.

--unquoted

Overrides report/quoted configuration setting.

Special options

--configreport ReportName

This defines the ReportName for which any subsequent -o|--columns, -O|--sort or -S|--select applies to. See also Main report specifics and Log report specifics for possible ReportName values.

--logonly

When an LVM command contains both main report and log report, this option suppresses the main report output and it causes the log report output to be displayed only.

--unbuffered

Overrides report/buffered configuration setting.

The FieldSet mentioned in the lists above is a set of field names where each field name is delimited by "," character. Field set definition, sorting and selection may be repeated on command line (-o+/-o- includes/excludes fields to/from current list, for all the other repeatable options, the last value typed for the option on the command line is used). The Selection is a string with selection criteria, see also Selection paragraph below for more information about constructing these criteria.

### Main report specifics
The main report currently encompasses these distinct subtypes, referenced by their name - ReportName as listed below. The command in parenthesis is representative command that uses the main report subtype by default. Each subtype has its own configuration setting for global field set definition as well as sort field definition (listed below each individual ReportName):

pv

representing report about Physical Volumes (pvs)

- report/pvs_cols

- report/pvs_sort

pvseg

representing report about Physical Volume Segments (pvs --segments)

- report/pvseg_cols

- report/pvseg_sort

vg

representing report about Volume Groups (vgs)

- report/vgs_cols

- report/vgs_sort

lv

representing report about Logical Volumes (lvs)

- report/lvs_cols

- report/lvs_sort

seg

representing report about Logical Volume Segments (lvs --segments)

- report/segs_cols

- report/segs_sort

full

representing report combining all of the above as a whole (lvm fullreport)

- report/pvs_cols_full

- report/pvs_sort_full

- report/pvsegs_cols_full

- report/pvseg_sort_full

- report/vgs_cols_full

- report/vgs_sort_full

- report/lvs_cols_full

- report/lvs_sort_full

- report/segs_cols_full

- report/segs_sort_full

devtype

representing report about device types (lvm devtypes)

- report/devtypes_cols

- report/devtypes_sort

Use pvs, vgs, lvs -o help or lvm devtypes -o help to get complete list of fields that you can use for main report. The list of fields in the help output is separated in groups based on which report type they belong to. Note that LVM can change final report type used if fields from different groups are combined together. Some of these combinations are not allowed in which case LVM will issue an error.

For all main report subtypes except full, it's not necessary to use --configreport ReportName to denote which report any subsequent -o, -O or -S option applies to as they always apply to the single main report type. Currently, lvm fullreport is the only command that includes more than one main report subtype. Therefore, the --configreport is particularly suitable for the full report if you need to configure each of its subreports in a different way.

### Log report specifics
You can enable log report with log/report_command_log configuration setting - this functionality is disabled by default. The log report contains a log collected during LVM command execution and then the log is displayed just like any other report known from main report. There is only one log report subtype as shown below together with related configuration settings for fields, sorting and selection:

log

representing log report

- log/command_log_cols

- log/command_log_sort

- log/command_log_selection

You always need to use --configreport log together with -o|--options, -O|--sort or -S|--selection to override configuration settings directly on command line for log report. When compared to main report, in addition to usual configuration settings for report fields and sorting, the log report has also configuration option for selection - report/command_log_selection. This configuration setting is provided for convenience so it's not necessary to use -S|--select on command line each time an LVM command is executed and we need the same selection criteria to be applied for log report. Default selection criteria used for log report are log/command_log_selection="!(log_type=status && message=success)". This means that, by default, log report doesn't display status messages about successful operation and it displays only rows with error, warning, print-type messages and messages about failure states (for more information, see log report content below).

Log report coverage

Currently, when running LVM commands directly (not in LVM shell), the log report covers command's processing stage which is the moment when LVM entities are iterated and processed one by one. It does not cover any command initialization nor command finalization stage. If there is any message issued out of log report's coverage range, such message goes directly to output, bypassing the log report. By default, that is standard error output for error and warning messages and standard output for common print-like messages.

When running LVM commands in LVM shell, the log report covers the whole LVM command's execution, including command's processing as well as initialization and finalization stage. So from this point of view, the log report coverage is complete for executed LVM commands. Note that there are still a few moments when LVM shell needs to initialize itself before it even enters the main loop in which it executes LVM commands. Also, there is a moment when LVM shell needs to prepare log report properly for next command executed in the shell and then, after the command's run, the shell needs to display the log report for that recently executed command. If there is a failure or any other message issued during this time, the LVM will bypass log report and display messages on output directly.

For these reasons and for completeness, it's not possible to rely fully on log report as the only indicator of LVM command's status and the only place where all messages issued during LVM command execution are collected. You always need to check whether the command has not failed out of log report's range by checking the non-report output too.

To help with this, LVM can separate output which you can then redirect to any custom file descriptor that you prepare before running an LVM command or LVM shell and then you make LVM to use these file descriptors for different kinds of output by defining environment variables with file descriptor numbers. See also LVM_OUT_FD, LVM_ERR_FD and LVM_REPORT_FD environment variable description in lvm(8) man page.

Also note that, by default, reports use the same file descriptor as common print-like messages, which is standard output. If you plan to use log report in your scripts or any external tool, you should use LVM_OUT_FD, LVM_ERR_FD and LVM_REPORT_FD to separate all output types to different file descriptors. For example, with bash, that would be:

LVM_OUT_FD=3 LVM_ERR_FD=4 LVM_REPORT_FD=5 <lvm command> 3>out_file 4>err_file 5>report_file

Where the <lvm_command> is either direct LVM command or LVM shell. You can collect all three types of output in particular files then.

Log report content

Each item in the log report consists of these set of fields providing various information:

Basic information (mandatory):

log_seq_num

Item sequence number. The sequence number is unique for each log item and it increases in the order of the log items as they appeared during LVM command execution.

log_type

Type of log for the item. Currently, these types are used:

status

for any status information that is logged

print

for any common message printed while the log is collected

error

for any error message printed while the log is collected

warn

for any warning message printed while the log is collected

log_context

Context of the log for the item. Currently, two contexts are identified:

shell

for the log collected in the outermost code before and after executing concrete LVM commands

processing

for the log collected while processing LVM entities during LVM command execution

Message (mandatory):

log_message

Any message associated with current item. For status log type, the message contains either success or failure denoting current state. For print, error and warn log types, the message contains the exact message of that type that got issued.

Object information (used only if applicable):

log_object_type field

Type of the object processed. Currently, these object types are recognized:

cmd

for command as a whole

orphan

for processing group of PVs not in any VG yet

pv

for PV processing

label

for direct PV label processing (without VG metadata)

vg

for VG processing

lv

for LV processing

log_object_name

Name of the object processed.

log_object_id

ID of the object processed.

log_object_group

A group where the processed object belongs to.

log_object_group_id

An ID of a group where the processed object belongs to.

Numeric status (used only if applicable):

log_errno

Error number associated with current item.

log_ret_code

Return code associated with current item.

You can also run lvm --configreport log -o help to to display complete list of fields that you may use for the log report.

### Selection
Selection is used for a report to display only rows that match selection criteria. All rows are displayed with the additional selected field (-o selected) displaying 1 if the row matches the Selection and 0 otherwise. The selection criteria are a set of statements combined by logical and grouping operators. The statement consists of a field name for which a set of valid values is defined using comparison operators. For complete list of fields names that you can use in selection, see the output of lvm -S help. The help output also contains type of values that each field displays enclosed in brackets.

List of operators recognized in selection criteria

Comparison operators (cmp_op)

=~

matching regular expression.

!~

not matching regular expression.

=

equal to.

!=

not equal to.

>=

greater than or equal to.

>

greater than

<=

less than or equal to.

<

less than.

Binary logical operators (cmp_log)

&&

all fields must match

,

all fields must match

||

at least one field must match

\#

at least one field must match

Unary logical operators

!

logical negation

Grouping operators

(

left parenthesis

)

right parenthesis

[

list start

]

list end

{

list subset start

}

list subset end

Field types and selection operands

Field type restricts the set of operators and values that you may use with the field when defining selection criteria. You can see field type for each field if you run lvm -S help where you can find the type name enclosed in square brackets. Currently, LVM recognizes these field types in reports:

string

for set of characters (for each string field type, you can use either string or regular expression - regex for the value used in selection criteria)

string list

for set of strings

number

for integer value

size

for integer or floating point number with size unit suffix (see also lvcreate(8) man page and description for "-L|--size" option for the list of recognized suffixes)

percent for floating point number with or without % suffix

(e.g. 50 or 50%)

time

for time values

When using string list in selection criteria, there are several ways how LVM can match string list fields from report, depending on what list grouping operator is used and what item separator is used within that set of items. Also, note that order of items does not matter here.

•

matching the set strictly where all items must match - use [ ], e.g. ["a","b","c"]

•

matching a subset of the set - use { } with "," or "&&" as item delimiter, e.g. {"a","b","c"}

•

matching an intersection with the set - use { } with "#" or "||" as item delimiter, e.g. {"a" || "b" || "c"}

When using time in your selection criteria, LVM can recognize various time formats using standard, absolute or freeform expressions. For examples demonstrating time expressions in selection criteria, see EXAMPLES section.

•

Standard time format

-

date

YYYY-MM-DD

YYYY-MM, auto DD=1

YYYY, auto MM=01 and DD=01

-

time

hh:mm:ss

hh:mm, auto ss=0

hh, auto mm=0, auto ss=0

-

timezone

+hh:mm or -hh:mm

+hh or -hh

The full date/time specification is YYYY-MM-DD hh:mm:ss. Users are able to leave date/time parts from right to left. Whenever these parts are left out, a range is assumed automatically with second granularity. For example:

```
"2015-07-07 9:51" means range of "2015-07-07 9:51:00" - "2015-07-07 9:51:59"
"2015-07" means range of "2015-07-01 0:00:00" - "2015-07-31 23:59:59"
"2015" means range of "2015-01-01 0:00:00" - "2015-12-31 23:59:59"
```

•

Absolute time format

Absolute time is defined as number of seconds since the Epoch (1970:01:01 00:00 +00:00).

-

@seconds

•

Freeform time format

- weekday names ("Sunday" - "Saturday" or abbreviated as "Sun" - "Sat")

- labels for points in time ("noon", "midnight")

- labels for a day relative to current day ("today", "yesterday")

- points back in time with relative offset from today (N is a number)

"N" "seconds" / "minutes" / "hours" / "days" / "weeks" / "years" "ago"

"N" "secs" / "mins" / "hrs" ... "ago"

"N" "s" / "m" / "h" ... "ago"

- time specification either in hh:mm:ss format or with AM/PM suffixes

- month names ("January" - "December" or abbreviated as "Jan" - "Dec")

Informal grammar specification

- STATEMENT = column cmp_op VALUE | STATEMENT log_op STATEMENT | (STATEMENT) | !(STATEMENT)

- VALUE = [VALUE log_op VALUE]

For list-based types: string list. Matches strictly. The log_op must always be of one type within the whole list value.

- VALUE = {VALUE log_op VALUE}

For list-based types: string list. Matches a subset. The log_op must always be of one type within the whole list value.

- VALUE = value

For scalar types: number, size, percent, string (or string regex).

## EXAMPLES

### Basic usage
We start our examples with default configuration - lvmconfig(8) is helpful command to display configuration settings which are currently used, including all configuration related to reporting. We will use it throughout examples below to display current configuration.

```
# lvmconfig --type full global/units global/suffix \

   report/output_format  report/compact_output \

   report/compact_output_cols report/aligned \

   report/headings report/separator \

   report/list_item_separator report/prefixes \

   report/quoted report/columns_as_rows \

   report/binary_values_as_numeric report/time_format \

   report/mark_hidden_devices report/two_word_unknown_device \

   report/buffered
units="h"
suffix=1
output_format="basic"
compact_output=0
compact_output_cols=""
aligned=1
headings=1
separator=" "
list_item_separator=","
prefixes=0
quoted=1
columns_as_rows=0
binary_values_as_numeric=0
time_format="%Y-%m-%d %T %z"
mark_hidden_devices=1
two_word_unknown_device=0
buffered=1
```

Also, we start with simple LVM layout with two PVs (/dev/sda, /dev/sdb), VG (vg) and two LVs (lvol0 and lvol1) in the VG. We display all possible reports as single commands here, see also pvs(8), vgs(8), lvs(8) man pages for more information. The field set for each report type is configured with configuration settings as we already mentioned in main report specifics section in this man page.

```
# lvmconfig --type full report/pvs_cols report/pvs_sort \

   report/pvsegs_cols report/pvsegs_sort report/vgs_cols \

   report/vgs_sort report/lvs_cols report/lvs_sort \

   report/segs_cols report/segs_sort
pvs_cols="pv_name,vg_name,pv_fmt,pv_attr,pv_size,pv_free"
pvs_sort="pv_name"
pvsegs_cols="pv_name,vg_name,pv_fmt,pv_attr,pv_size,pv_free,

             pvseg_start,pvseg_size"
pvsegs_sort="pv_name,pvseg_start"
vgs_cols="vg_name,pv_count,lv_count,snap_count,vg_attr,vg_size,vg_free"
vgs_sort="vg_name"
lvs_cols="lv_name,vg_name,lv_attr,lv_size,pool_lv,origin,move_pv,

          mirror_log,copy_percent,convert_lv"
lvs_sort="vg_name,lv_name"
segs_cols="lv_name,vg_name,lv_attr,stripes,segtype,seg_size"
segs_sort="vg_name,lv_name,seg_start"
```

```
# pvs

  PV         VG Fmt  Attr PSize   PFree

  /dev/sda   vg lvm2 a--  100.00m 88.00m

  /dev/sdb   vg lvm2 a--  100.00m 92.00m
```

```
# pvs --segments

  PV         VG Fmt  Attr PSize   PFree  Start SSize

  /dev/sda   vg lvm2 a--  100.00m 88.00m     0     1

  /dev/sda   vg lvm2 a--  100.00m 88.00m     1     1

  /dev/sda   vg lvm2 a--  100.00m 88.00m     2     1

  /dev/sda   vg lvm2 a--  100.00m 88.00m     3    22

  /dev/sdb   vg lvm2 a--  100.00m 92.00m     0     1

  /dev/sdb   vg lvm2 a--  100.00m 92.00m     1     1

  /dev/sdb   vg lvm2 a--  100.00m 92.00m     2    23
```

```
# vgs

  VG #PV #LV #SN Attr   VSize   VFree

  vg   2   2   0 wz--n- 200.00m 180.00m
```

```
# lvs

  LV    VG Attr       LSize Pool Origin Move Log Cpy%Sync Convert

  lvol0 vg -wi-a----- 4.00m

  lvol1 vg rwi-a-r--- 4.00m                      100.00
```

```
# lvs --segments

  LV    VG Attr       #Str Type   SSize

  lvol0 vg -wi-a-----    1 linear 4.00m

  lvol1 vg rwi-a-r---    2 raid1  4.00m
```

We will use report/lvs_cols and report/lvs_sort configuration settings to define our own list of fields to use and to sort by that is different from defaults. You can do this for other reports in same manner with report/{pvs,pvseg,vgs,seg}_{cols,sort} configuration settings. Also note that in the example below, we don't display the "lv_time" field even though we're using it for sorting - this is allowed.

```
# lvmconfig --type full report/lvs_cols report/lvs_sort
lvs_cols="lv_name,lv_size,origin,pool_lv,copy_percent"
lvs_sort="-lv_time"
```

```
# lvs

  LV    LSize Origin Pool Cpy%Sync

  lvol1 4.00m             100.00

  lvol0 4.00m
```

You can use -o|--options command line option to override current configuration directly on command line.

```
# lvs -o lv_name,lv_size

  LV    LSize

  lvol1 4.00m

  lvol0 4.00m
```

```
# lvs -o+lv_layout

  LV    LSize Origin Pool Cpy%Sync Layout

  lvol1 4.00m             100.00   raid,raid1

  lvol0 4.00m                      linear
```

```
# lvs -o-origin

  LV    LSize Pool Cpy%Sync

  lvol1 4.00m      100.00

  lvol0 4.00m
```

```
# lvs -o lv_name,lv_size,origin -o+lv_layout -o-origin -O lv_name

  LV    LSize Layout

  lvol0 4.00m linear

  lvol1 4.00m raid,raid1
```

You can obtain the same information with single command where all the information about PVs, PV segments, LVs and LV segments are obtained per VG under a single VG lock for consistency, see also lvm fullreport(8) man page for more information. The fullreport has its own configuration settings to define field sets to use, similar to individual reports as displayed above, but configuration settings have "_full" suffix now. This way, it's possible to configure different sets of fields to display and to sort by for individual reports as well as the full report.

```
# lvmconfig --type full report/pvs_cols_full \

   report/pvs_sort_full report/pvsegs_cols_full \

   report/pvsegs_sort_full report/vgs_cols_full \

   report/vgs_sort_full report/lvs_cols_full \

   report/lvs_sort_full report/segs_cols_full \

   report/segs_sort_full
pvs_cols_full="pv_name,vg_name"
pvs_sort_full="pv_name"
pvsegs_cols_full="pv_name,pvseg_start,pvseg_size"
pvsegs_sort_full="pv_uuid,pvseg_start"
vgs_cols_full="vg_name"
vgs_sort_full="vg_name"
lvs_cols_full="lv_name,vg_name"
lvs_sort_full="vg_name,lv_name"
segs_cols_full="lv_name,seg_start,seg_size"
segs_sort_full="lv_uuid,seg_start"
```

```
# lvm fullreport

  VG

  vg

  PV         VG

  /dev/sda   vg

  /dev/sdb   vg

  LV    VG

  lvol0 vg

  lvol1 vg

  PV         Start SSize

  /dev/sda       0     1

  /dev/sda       1     1

  /dev/sda       2     1

  /dev/sda       3    22

  /dev/sdb       0     1

  /dev/sdb       1     1

  /dev/sdb       2    23

  LV    Start SSize

  lvol0    0  4.00m

  lvol1    0  4.00m
```

### Automatic output compaction
If you look at the lvs output above, you can see that the report also contains fields for which there is no information to display (e.g. the columns under "Origin" and "Pool" heading - the "origin" and "pool_lv" fields). LVM can automatically compact report output so such fields are not included in final output. To enable this feature and to compact all fields, use report/compact_output=1 in your configuration.

```
# lvmconfig --type full report/compact_output
compact_output=1
```

```
# lvs

  LV    LSize Cpy%Sync

  lvol1 4.00m 100.00

  lvol0 4.00m
```

```
# lvs vg/lvol0

  LV    LSize

  lvol0 4.00m
```

Alternatively, you can define which fields should be compacted by configuring report/compact_output_cols configuration setting (or -o|--options # command line option).

```
# lvmconfig --type full report/compact_output report/compact_output_cols
compact_output=0
compact_output_cols="origin"
```

```
# lvs

  LV    LSize Pool Cpy%Sync

  lvol1 4.00m      100.00

  lvol0 4.00m
```

```
# lvs vg/lvol0

  LV    LSize Pool

  lvol0 4.00m
```

```
# lvs -o#pool_lv

  LV    LSize Origin Cpy%Sync

  lvol1 4.00m        100.00

  lvol0 4.00m
```

We will use report/compact_output=1 for subsequent examples.

### Further formatting options
By default, LVM displays sizes in reports in human-readable form which means that the most suitable unit is used so it's easy to read. You can use report/units configuration setting (or --units option directly on command line) and report/suffix configuration setting (or --nosuffix command line option) to change this.

```
# lvs --units b --nosuffix

  LV    LSize   Cpy%Sync

  lvol1 4194304 100.00

  lvol0 4194304
```

If you want to configure whether report headings are displayed or not, use report/headings configuration settings (or --noheadings command line option).

```
# lvs --noheadings

  lvol1 4.00m 100.00

  lvol0 4.00m
```

In some cases, it may be useful to display report content as key=value pairs where key here is actually the field name. Use report/prefixes configuration setting (or --nameprefixes command line option) to switch between standard output and the key=value output. The key=value pair is the output that is suitable for use in scripts and for other tools to parse easily. Usually, you also don't want to display headings with the output that has these key=value pairs.

```
# lvs --noheadings --nameprefixes

  LVM2_LV_NAME='lvol1' LVM2_LV_SIZE='4.00m' LVM2_COPY_PERCENT='100.00'

  LVM2_LV_NAME='lvol0' LVM2_LV_SIZE='4.00m' LVM2_COPY_PERCENT=''
```

To define whether quotation marks in key=value pairs should be used or not, use report/quoted configuration setting (or --unquoted command line option).

```
# lvs --noheadings --nameprefixes --unquoted

  LVM2_LV_NAME=lvol1 LVM2_LV_SIZE=4.00m LVM2_COPY_PERCENT=100.00

  LVM2_LV_NAME=lvol0 LVM2_LV_SIZE=4.00m LVM2_COPY_PERCENT=
```

For easier parsing, you can even transpose the report so each column now becomes a row in the output. This is done with report/output_as_rows configuration setting (or --rows command line option).

```
# lvs --noheadings --nameprefixes --unquoted --rows

  LVM2_LV_NAME=lvol1 LVM2_LV_NAME=lvol0

  LVM2_LV_SIZE=4.00m LVM2_LV_SIZE=4.00m

  LVM2_COPY_PERCENT=100.00 LVM2_COPY_PERCENT=
```

Use report/separator configuration setting (or --separator command line option) to define your own field separator to use.

```
# lvs --noheadings --nameprefixes --unquoted --separator " | "

  LVM2_LV_NAME=lvol1 | LVM2_LV_SIZE=4.00m | LVM2_COPY_PERCENT=100.00

  LVM2_LV_NAME=lvol0 | LVM2_LV_SIZE=4.00m | LVM2_COPY_PERCENT=
```

If you are using your own separator, the columns in the output are not aligned by default. Use report/aligned configuration setting (or --aligned command line option) for LVM to add extra spaces in report to align the output properly.

```
# lvs --separator " | "

  LV | LSize | Cpy%Sync

  lvol1 | 4.00m | 100.00

  lvol0 | 4.00m |
```

```
# lvs --separator " | " --aligned

  LV    | LSize | Cpy%Sync

  lvol1 | 4.00m | 100.00

  lvol0 | 4.00m |
```

Let's display one one more field in addition ("lv_tags" in this example) for the lvs report output.

```
# lvs -o+lv_tags

  LV    LSize Cpy%Sync LV Tags

  lvol1 4.00m 100.00

  lvol0 4.00m          tagA,tagB
```

The "LV Tags" column in the example above displays two list values, separated by "," character for LV lvol0. If you need different list item separator, use report/list_item_separator configuration setting its definition.

```
# lvmconfig --type full report/list_item_separator
list_item_separator=";"
```

```
# lvs -o+tags

  LV    LSize Cpy%Sync LV Tags

  lvol1 4.00m 100.00

  lvol0 4.00m          tagA;tagB
```

But let's still use the original "," character for list_item_separator for subsequent examples.

Format for any of time values displayed in reports can be configured with report/time_format configuretion setting. By default complete date and time is displayed, including timezone.

```
# lvmconfig --type full report/time_format
time_format="%Y-%m-%d %T %z"
```

```
# lvs -o+time

  LV    LSize Cpy%Sync CTime

  lvol1 4.00m 100.00   2016-08-29 12:53:36 +0200

  lvol0 4.00m          2016-08-29 10:15:17 +0200
```

We can change time format in similar way as we do when using date(1) command or strftime(3) function (lvmconfig --type default --withcomments report/time_format will give you complete list of available formatting options). In the example below, we decided to use %s for number of seconds since Epoch (1970-01-01 UTC).

```
# lvmconfig --type full report/time_format
time_format="%s"
```

```
# lvs

  LV    Attr       LSize Cpy%Sync LV Tags   CTime

  lvol1 rwi-a-r--- 4.00m 100.00             1472468016

  lvol0 -wi-a----- 4.00m          tagA,tagB 1472458517
```

The lvs does not display hidden LVs by default - to include these LVs in the output, you need to use -a|--all command line option. Names for these hidden LVs are displayed within square brackets.

```
# lvs -a

  LV               LSize Cpy%Sync

  lvol1            4.00m 100.00

  [lvol1_rimage_0] 4.00m

  [lvol1_rmeta_0]  4.00m

  [lvol1_rimage_1] 4.00m

  [lvol1_rmeta_1]  4.00m

  lvol0            4.00m
```

You can configure LVM to display the square brackets for hidden LVs or not with report/mark_hidden_devices configuration setting.

```
# lvmconfig --type full report/mark_hidden_devices
mark_hidden_devices=0
```

```
# lvs -a

  LV             LSize Cpy%Sync

  lvol1          4.00m 100.00

  lvol1_rimage_0 4.00m

  lvol1_rmeta_0  4.00m

  lvol1_rimage_1 4.00m

  lvol1_rmeta_1  4.00m

  lvol0          4.00m
```

It's not recommended to use LV marks for hidden devices to decide whether the LV is the one to use by end users or not. Please, use "lv_role" field instead which can report whether the LV is "public" or "private". The private LVs are used by LVM only and they should not be accessed directly by end users.

```
# lvs -a -o+lv_role

  LV             LSize Cpy%Sync Role

  lvol1          4.00m 100.00   public

  lvol1_rimage_0 4.00m          private,raid,image

  lvol1_rmeta_0  4.00m          private,raid,metadata

  lvol1_rimage_1 4.00m          private,raid,image

  lvol1_rmeta_1  4.00m          private,raid,metadata

  lvol0          4.00m          public
```

Some of the reporting fields that LVM reports are of binary nature. For such fields, it's either possible to display word representation of the value (this is used by default) or numeric value (0/1 or -1 in case the value is undefined).

```
# lvs -o+lv_active_locally

  LV    LSize Cpy%Sync ActLocal

  lvol1 4.00m 100.00   active locally

  lvol0 4.00m          active locally
```

We can change the way how these binary values are displayed with report/binary_values_as_numeric configuration setting.

```
# lvmconfig --type full report/binary_values_as_numeric
binary_values_as_numeric=1
```

```
# lvs -o+lv_active_locally

  LV    LSize Cpy%Sync ActLocal

  lvol1 4.00m 100.00            1

  lvol0 4.00m                   1
```

### Changing output format
LVM can output reports in different formats - use report/output_format configuration setting (or --reportformat command line option) to swith the report output format. Currently, LVM supports "basic" (all the examples we used above used this format) and "JSON" output format.

```
# lvs -o lv_name,lv_size --reportformat json

  {

      "report": [

          {

              "lv": [

                  {"lv_name":"lvol1", "lv_size":"4.00m"},

                  {"lv_name":"lvol0", "lv_size":"4.00m"}

              ]

          }

      ]

  }
```

Note that some configuration settings and command line options have no effect with certain report formats. For example, with JSON output, it doesn't have any meaning to use report/aligned (--aligned), report/noheadings (--noheadings), report/columns_as_rows (--rows) or report/buffered (--unbuffered). All these configuration settings and command line options are ignored if using the JSON report output format.

### Selection
If you need to select only specific rows from report, you can use LVM's report selection feature. If you call lvm -S help, you'll get quick help on selection. The help contains list of all fields that LVM can use in reports together with its type enclosed in square brackets. The example below contains a line from lvs -S help.

```
# lvs -S help

    ...

    lv_size                - Size of LV in current units. [size]

    ...
```

This line tells you you that the "lv_size" field is of "size" type. If you look at the bottom of the help output, you can see section about "Selection operators" and its "Comparison operators".

```
# lvs -S help

 ...
Selection operators
-------------------
Comparison operators:

   =~  - Matching regular expression. [regex]

   !~  - Not matching regular expression. [regex]

    =  - Equal to. [number, size, percent, string, string list, time]

   !=  - Not equal to. [number, size, percent, string, string_list, time]

   >=  - Greater than or equal to. [number, size, percent, time]

    >  - Greater than. [number, size, percent, time]

   <=  - Less than or equal to. [number, size, percent, time]

    <  - Less than. [number, size, percent, time]
since  - Since specified time (same as '>='). [time]
after  - After specified time (same as '>'). [time]
until  - Until specified time (same as '<='). [time]
before - Before specified time (same as '<'). [time]

 ...
```

Here you can match comparison operators that you may use with the "lv_size" field which is of type "size" - it's =, !=, >=, >, <= and <. You can find applicable comparison operators for other fields and other field types the same way.

To demonstrate selection functionality in LVM, we will create more LVs in addition to lvol0 and lvol1 we used in our previous examples.

```
# lvs -o name,size,origin,snap_percent,tags,time

  LV    LSize Origin Snap%  LV Tags        CTime

  lvol4 4.00m lvol2  24.61                 2016-09-09 16:57:44 +0200

  lvol3 4.00m lvol2  5.08                  2016-09-09 16:56:48 +0200

  lvol2 8.00m               tagA,tagC,tagD 2016-09-09 16:55:12 +0200

  lvol1 4.00m                              2016-08-29 12:53:36 +0200

  lvol0 4.00m               tagA,tagB      2016-08-29 10:15:17 +0200
```

When selecting size and percent fields, we don't need to use units. For sizes, default "m" (for MiB) is used - this is the same behaviour as already used for LVM commands when specifying sizes (e.g. lvcreate -L). For percent fields, "%" is assumed automatically if it's not specified. The example below also demonstrates how several criteria can be combined together.

```
# lvs -o name,size,snap_percent -S 'size=8m'

  LV    LSize

  lvol2 8.00m
```

```
# lvs -o name,size,snap_percent -S 'size=8'

  LV    LSize

  lvol2 8.00m
```

```
# lvs -o name,size,snap_percent -S 'size < 5000k'

  LV    LSize Snap%

  lvol4 4.00m 24.61

  lvol3 4.00m 5.08

  lvol1 4.00m

  lvol0 4.00m
```

```
# lvs -o name,size,snap_percent -S 'size < 5000k && snap_percent > 20'

  LV    LSize Snap%

  lvol4 4.00m 24.61
```

```
# lvs -o name,size,snap_percent \

    -S '(size < 5000k && snap_percent > 20%) || name=lvol2'

  LV    LSize Snap%

  lvol4 4.00m 24.61

  lvol2 8.00m
```

You can also use selection together with processing-oriented commands.

```
# lvchange --addtag test -S 'size < 5000k'

  Logical volume vg/lvol1 changed.

  Logical volume vg/lvol0 changed.

  Logical volume vg/lvol3 changed.

  Logical volume vg/lvol4 changed.
```

```
# lvchange --deltag test -S 'tags = test'

  Logical volume vg/lvol1 changed.

  Logical volume vg/lvol0 changed.

  Logical volume vg/lvol3 changed.

  Logical volume vg/lvol4 changed.
```

LVM can recognize more complex values used in selection criteria for string list and time field types. For string lists, you can match whole list strictly, its subset or intersection. Let's take "lv_tags" field as an example - we select only rows which contain "tagA" within tags field. We're using { } to denote that we're interested in subset that matches. If the subset has only one item, we can leave out { }.

```
# lvs -o name,tags -S 'tags={tagA}'

  LV    LV Tags

  lvol2 tagA,tagC,tagD

  lvol0 tagA,tagB
```

```
# lvs -o name,tags -S 'tags=tagA'

  LV    LV Tags

  lvol2 tagA,tagC,tagD

  lvol0 tagA,tagB
```

Depending on whether we use "&&" (or ",") or "||" ( or "#") as delimiter for items in the set we define in selection criterion for string list, we either match subset ("&&" or ",") or even intersection ("||" or "#").

```
# lvs -o name,tags -S 'tags={tagA,tagC,tagD}'

  LV    LV Tags

  lvol2 tagA,tagC,tagD
```

```
# lvs -o name,tags -S 'tags={tagA || tagC || tagD}'

  LV    LV Tags

  lvol2 tagA,tagC,tagD

  lvol0 tagA,tagB
```

To match the complete set, use [ ] with "&&" (or ",") as delimiter for items. Also note that the order in which we define items in the set is not relevant.

```
# lvs -o name,tags -S 'tags=[tagA]'
```

```
# lvs -o name,tags -S 'tags=[tagB,tagA]'

  LV    LV Tags

  lvol0 tagA,tagB
```

If you use [ ] with "||" (or "#"), this is exactly the same as using { }.

```
# lvs -o name,tags -S 'tags=[tagA || tagC || tagD]'

  LV    LV Tags

  lvol2 tagA,tagC,tagD

  lvol0 tagA,tagB
```

To match a set with no items, use "" to denote this (note that we have output compaction enabled so the "LV Tags" column is not displayed in the example below because it's blank and so it gets compacted).

```
# lvs -o name,tags -S 'tags=""'

  LV

  lvol4

  lvol3

  lvol1
```

```
# lvs -o name,tags -S 'tags!=""'

  LV    LV Tags

  lvol2 tagA,tagC,tagD

  lvol0 tagA,tagB
```

When doing selection based on time fields, we can use either standard, absolute or freeform time expressions in selection criteria. Examples below are using standard forms.

```
# lvs -o name,time

  LV    CTime

  lvol4 2016-09-09 16:57:44 +0200

  lvol3 2016-09-09 16:56:48 +0200

  lvol2 2016-09-09 16:55:12 +0200

  lvol1 2016-08-29 12:53:36 +0200

  lvol0 2016-08-29 10:15:17 +0200
```

```
# lvs -o name,time -S 'time since "2016-09-01"'

  LV    CTime

  lvol4 2016-09-09 16:57:44 +0200

  lvol3 2016-09-09 16:56:48 +0200

  lvol2 2016-09-09 16:55:12 +0200
```

```
# lvs -o name,time -S 'time since "2016-09-09 16:56"'

  LV    CTime

  lvol4 2016-09-09 16:57:44 +0200

  lvol3 2016-09-09 16:56:48 +0200
```

```
# lvs -o name,time -S 'time since "2016-09-09 16:57:30"'

  LV    CTime

  lvol4 2016-09-09 16:57:44 +0200
```

```
# lvs -o name,time \

    -S 'time since "2016-08-29" && time until "2016-09-09 16:55:12"'

  LV    CTime

  lvol2 2016-09-09 16:55:12 +0200

  lvol1 2016-08-29 12:53:36 +0200

  lvol0 2016-08-29 10:15:17 +0200
```

```
# lvs -o name,time \

    -S 'time since "2016-08-29" && time before "2016-09-09 16:55:12"'

  LV    CTime

  lvol1 2016-08-29 12:53:36 +0200

  lvol0 2016-08-29 10:15:17 +0200
```

Time operators have synonyms: ">=" for since, "<=" for until, ">" for "after" and "<" for "before".

```
# lvs -o name,time \

    -S 'time >= "2016-08-29" && time <= "2016-09-09 16:55:30"'

  LV    CTime

  lvol2 2016-09-09 16:55:12 +0200

  lvol1 2016-08-29 12:53:36 +0200

  lvol0 2016-08-29 10:15:17 +0200
```

```
# lvs -o name,time \

    -S 'time since "2016-08-29" && time < "2016-09-09 16:55:12"'

  LV    CTime

  lvol1 2016-08-29 12:53:36 +0200

  lvol0 2016-08-29 10:15:17 +0200
```

Example below demonstrates using absolute time expression.

```
# lvs -o name,time --config report/time_format="%s"

  LV    CTime

  lvol4 1473433064

  lvol3 1473433008

  lvol2 1473432912

  lvol1 1472468016

  lvol0 1472458517
```

```
# lvs -o name,time -S 'time since @1473433008'

  LV    CTime

  lvol4 2016-09-09 16:57:44 +0200

  lvol3 2016-09-09 16:56:48 +0200
```

Examples below demonstrates using freeform time expressions.

```
# lvs -o name,time -S 'time since "2 weeks ago"'

  LV    CTime

  lvol4 2016-09-09 16:57:44 +0200

  lvol3 2016-09-09 16:56:48 +0200

  lvol2 2016-09-09 16:55:12 +0200

  lvol1 2016-08-29 12:53:36 +0200

  lvol0 2016-08-29 10:15:17 +0200
```

```
# lvs -o name,time -S 'time since "1 week ago"'

  LV    CTime

  lvol4 2016-09-09 16:57:44 +0200

  lvol3 2016-09-09 16:56:48 +0200

  lvol2 2016-09-09 16:55:12 +0200
```

```
# lvs -o name,time -S 'time since "2 weeks ago"'

  LV    CTime

  lvol1 2016-08-29 12:53:36 +0200

  lvol0 2016-08-29 10:15:17 +0200
```

```
# lvs -o name,time -S 'time before "1 week ago"'

  LV    CTime

  lvol1 2016-08-29 12:53:36 +0200

  lvol0 2016-08-29 10:15:17 +0200
```

```
# lvs -o name,time -S 'time since "68 hours ago"'

  LV    CTime

  lvol4 2016-09-09 16:57:44 +0200

  lvol3 2016-09-09 16:56:48 +0200

  lvol2 2016-09-09 16:55:12 +0200
```

```
# lvs -o name,time -S 'time since "1 year 3 months ago"'

  LV    CTime

  lvol4 2016-09-09 16:57:44 +0200

  lvol3 2016-09-09 16:56:48 +0200

  lvol2 2016-09-09 16:55:12 +0200

  lvol1 2016-08-29 12:53:36 +0200

  lvol0 2016-08-29 10:15:17 +0200
```

### Command log reporting
As described in categorization based on reporting facility section at the beginning of this document, both report-oriented and processing-oriented LVM commands can report the command log if this is enabled with log/report_command_log configuration setting. Just like any other report, we can set the set of fields to display (log/command_log_cols) and to sort by (log/command_log_sort) for this report.

```
# lvmconfig --type full log/report_command_log log/command_log_cols \

   log/command_log_sort log/command_log_selection
report_command_log=1
command_log_cols="log_seq_num,log_type,log_context,log_object_type,

                  log_object_name,log_object_group,log_message,

                  log_errno,log_ret_code"
command_log_sort="log_seq_num"
command_log_selection="!(log_type=status && message=success)"
```

```
# lvs

  Logical Volume

  ==============

  LV    LSize Cpy%Sync

  lvol1 4.00m 100.00

  lvol0 4.00m
```

```
  Command Log

  ===========

  Seq LogType Context ObjType ObjName ObjGrp  Msg     Errno RetCode
```

As you can see, the command log is empty (it contains only field names). By default, LVM uses selection on the command log report and this case no row matched the selection criteria, see also log report specifics section in this document for more information. We're displaying complete log report in the example below where we can see that both LVs lvol0 and lvol1 were successfully processed as well as the VG vg they are part of.

```
# lvmconfig --type full log/command_log_selection
command_log_selection="all"
```

```
# lvs

  Logical Volume

  ==============

  LV    LSize Cpy%Sync

  lvol1 4.00m 100.00

  lvol0 4.00m
```

```
  Command Log

  ===========

  Seq LogType Context    ObjType ObjName ObjGrp  Msg     Errno RetCode

    1 status  processing lv      lvol0   vg      success     0       1

    2 status  processing lv      lvol1   vg      success     0       1

    3 status  processing vg      vg              success     0       1
```

```
# lvchange -an vg/lvol1

  Command Log

  ===========

  Seq LogType Context    ObjType ObjName ObjGrp  Msg     Errno RetCode

    1 status  processing lv      lvol1   vg      success     0       1

    2 status  processing vg      vg              success     0       1
```

### Handling multiple reports per single command
To configure the log report directly on command line, we need to use --configreport option before we start any -o|--options, -O|--sort or -S|--select that is targeted for log report.

```
# lvs -o lv_name,lv_size --configreport log -o log_object_type, \

   log_object_name,log_message,log_ret_code

  Logical Volume

  ==============

  LV    LSize

  lvol1 4.00m

  lvol0 4.00m
```

```
  Command Log

  ===========

  ObjType ObjName Msg     RetCode

  lv      lvol0   success       1

  lv      lvol1   success       1

  vg      vg      success       1
```

The lvm fullreport, with or without log report, consists of several reports - the --configreport is also used to target particular subreport here.

Below is an extended example with lvm fullreport to illustrate combination of various options. The report output is in JSON format. Also, we configure "vg", "pvseg", "seg" and "log" subreport to contain only specified fields. For the "pvseg" subreport, we're interested only in PV names having "sda" in their name. For the "log" subreport we're interested only in log lines related to either "lvol0" object or object having "sda" in its name. Also, for the log subreport we define ordering to be based on "log_object_type" field.

```
# lvm fullreport --reportformat json \

   --configreport vg -o vg_name,vg_size \

   --configreport pvseg -o pv_name,pvseg_start \

                        -S 'pv_name=~sda' \

   --configreport seg -o lv_name,seg_start \

   --configreport log -o log_object_type,log_object_name \

                      -O log_object_type \

                      -S 'log_object_name=lvol0 || \

                          log_object_name=~sda'

  {

      "report": [

          {

              "vg": [

                  {"vg_name":"vg", "vg_size":"200.00m"}

              ]

              ,

              "pv": [

                  {"pv_name":"/dev/sda", "vg_name":"vg"},

                  {"pv_name":"/dev/sdb", "vg_name":"vg"}

              ]

              ,

              "lv": [

                  {"lv_name":"lvol0", "vg_name":"vg"},

                  {"lv_name":"lvol1", "vg_name":"vg"}

              ]

              ,

              "pvseg": [

                  {"pv_name":"/dev/sda", "pvseg_start":"0"},

                  {"pv_name":"/dev/sda", "pvseg_start":"1"},

                  {"pv_name":"/dev/sda", "pvseg_start":"2"},

                  {"pv_name":"/dev/sda", "pvseg_start":"3"}

              ]

              ,

              "seg": [

                  {"lv_name":"lvol0", "seg_start":"0 "},

                  {"lv_name":"lvol1", "seg_start":"0 "}

              ]

          }

      ]

      ,

      "log": [

          {"log_object_type":"lv", "log_object_name":"lvol0"},

          {"log_object_type":"lv", "log_object_name":"lvol0"},

          {"log_object_type":"pv", "log_object_name":"/dev/sda"},

          {"log_object_type":"pv", "log_object_name":"/dev/sda"},

      ]

  }
```

### Report extensions for LVM shell
As already stated in log report coverage paragraph under log report specifics in this documentation, when using LVM shell the log report coverage is wider. There's also special command designed to query last command's log report in the LVM shell - the lastlog command.

The example below illustrates a situation where we called lvs command. After that, we inspected the log report with the lastlog, without any selection so all the log report is displayed on output. Then we called lastlog further, giving various selection criteria. Then we ran unknown LVM command "abc" for which the log report displays appropriate failure state.

```
# lvm
lvm> lvs

  Logical Volume

  ==============

  LV    LSize Cpy%Sync

  lvol1 4.00m 100.00

  lvol0 4.00m
```

```
  Command Log

  ===========

  Seq LogType Context    ObjType ObjName ObjGrp  Msg     Errno RetCode

    1 status  processing lv      lvol0   vg      success     0       1

    2 status  processing lv      lvol1   vg      success     0       1

    3 status  processing vg      vg              success     0       1

    4 status  shell      cmd     lvs             success     0       1
```

```
lvm> lastlog

  Command Log

  ===========

  Seq LogType Context    ObjType ObjName ObjGrp  Msg     Errno RetCode

    1 status  processing lv      lvol0   vg      success     0       1

    2 status  processing lv      lvol1   vg      success     0       1

    3 status  processing vg      vg              success     0       1

    4 status  shell      cmd     lvs             success     0       1
```

```
lvm> lastlog -S log_object_type=lv

  Command Log

  ===========

  Seq LogType Context    ObjType ObjName ObjGrp  Msg     Errno RetCode

    1 status  processing lv      lvol0   vg      success     0       1

    2 status  processing lv      lvol1   vg      success     0       1
```

```
lvm> lastlog -S log_context=shell

  Command Log

  ===========

  Seq LogType Context ObjType ObjName ObjGrp  Msg     Errno RetCode

    4 status  shell   cmd     lvs             success     0       1
```

```
lvm> abc

  Command Log

  ===========

  Seq LogType Context ObjType ObjName ObjGrp  Msg                                 Errno RetCode

    1 error   shell   cmd     abc             No such command 'abc'.  Try 'help'.    -1       0

    2 status  shell   cmd     abc             failure                                -1       2
```

## SEE ALSO
lvm(8), lvmconfig(8), lvm fullreport(8), lvcreate(8),

lvs(8), pvs(8), vgs(8),

date(1), strftime(3)


lvmsystemid

title: lvmsystemid(7)

summary: LVM system ID

text:
# lvmsystemid(7)

## NAME
lvmsystemid — LVM system ID

## DESCRIPTION
The lvm(8) system ID restricts Volume Group (VG) access to one host. This is useful when a VG is placed on shared storage devices, or when local devices are visible to both host and guest operating systems. In cases like these, a VG can be visible to multiple hosts at once, and some mechanism is needed to protect it from being used by more than one host at a time.

A VG's system ID identifies one host as the VG owner. The host with a matching system ID can use the VG and its LVs, while LVM on other hosts will ignore it. This protects the VG from being accidentally used from other hosts.

The system ID is a string that uniquely identifies a host. It can be configured as a custom value, or it can be assigned automatically by LVM using some unique identifier already available on the host, e.g. machine-id or uname.

When a new VG is created, the system ID of the local host is recorded in the VG metadata. The creating host then owns the new VG, and LVM on other hosts will ignore it. When an existing, exported VG is imported (vgimport), the system ID of the local host is saved in the VG metadata, and the importing host owns the VG.

A VG without a system ID can be used by LVM on any host where the VG's devices are visible. When system IDs are not used, device filters should be configured on all hosts to exclude the VG's devices from all but one host.

A foreign VG is a VG seen by a host with an unmatching system ID, i.e. the system ID in the VG metadata does not match the system ID configured on the host. If the host has no system ID, and the VG does, the VG is foreign and LVM will ignore it. If the VG has no system ID, access is unrestricted, and LVM can access it from any host, whether the host has a system ID or not.

Changes to a host's system ID and a VG's system ID can be made in limited circumstances (see vgexport and vgimport). Improper changes can result in a host losing access to its VG, or a VG being accidentally damaged by access from an unintended host. Even limited changes to the VG system ID may not be perfectly reflected across hosts. A more coherent view of shared storage requires an inter-host locking system to coordinate access.

Valid system ID characters are the same as valid VG name characters. If a system ID contains invalid characters, those characters are omitted and remaining characters are used. If a system ID is longer than the maximum name length, the characters up to the maximum length are used. The maximum length of a system ID is 128 characters.

Print the system ID of a VG to check if it is set:

vgs -o systemid VG

Print the system ID of the local host to check if it is configured:

lvm systemid

### Limitations and warnings
To benefit fully from system ID, all hosts should have a system ID configured, and all VGs should have a system ID set. Without any method to restrict access, e.g. system ID or device filters, a VG that is visible to multiple hosts can be accidentally damaged or destroyed.

•

A VG without a system ID can be used without restriction from any host where it is visible, even from hosts that have a system ID.

•

Many VGs will not have a system ID set because LVM has not enabled it by default, and even when enabled, many VGs were created before the feature was added to LVM or enabled. A system ID can be assigned to these VGs by using vgchange --systemid (see below).

•

Two hosts should not be assigned the same system ID. Doing so defeats the purpose of distinguishing different hosts with this value.

•

Orphan PVs (or unused devices) on shared storage are unprotected by the system ID feature. Commands that use these PVs, such as vgcreate or vgextend, are not prevented from performing conflicting operations and corrupting the PVs. See the orphans section for more information.

•

The system ID does not protect devices in a VG from programs other than LVM.

•

A host using an old LVM version (without the system ID feature) will not recognize a system ID set in VGs. The old LVM can read a VG with a system ID, but is prevented from writing to the VG (or its LVs). The system ID feature changes the write mode of a VG, making it appear read-only to previous versions of LVM. This also means that if a host downgrades to the old LVM version, it would lose access to any VGs it had created with a system ID. To avoid this, the system ID should be removed from local VGs before downgrading LVM to a version without the system ID feature.

### Types of VG access
A local VG is meant to be used by a single host.

A shared or clustered VG is meant to be used by multiple hosts.

These can be further distinguished as:

Unrestricted:

A local VG that has no system ID. This VG type is unprotected and accessible to any host.

Owned:

A local VG that has a system ID set, as viewed from the host with a matching system ID (the owner). This VG type is accessible to the host.

Foreign:

A local VG that has a system ID set, as viewed from any host with an unmatching system ID (or no system ID). It is owned by another host. This VG type is not accessible to the host.

Exported:

A local VG that has been exported with vgexport and has no system ID. This VG type can only be accessed by vgimport which will change it to owned.

Shared:

A shared or "lockd" VG has the lock_type set and has no system ID. A shared VG is meant to be used on shared storage from multiple hosts, and is only accessible to hosts using lvmlockd. Applicable only if LVM is compiled with lvmlockd support.

Clustered:

A clustered or "clvm" VG has the clustered flag set and has no system ID. A clustered VG is meant to be used on shared storage from multiple hosts, and is only accessible to hosts using clvmd. Applicable only if LVM is compiled with clvm support.

### Host system ID configuration
A host's own system ID can be defined in a number of ways. lvm.conf global/system_id_source defines the method LVM will use to find the local system ID:

none

LVM will not use a system ID. LVM is allowed to access VGs without a system ID, and will create new VGs without a system ID. An undefined system_id_source is equivalent to none. lvm.conf

```
global {

    system_id_source = "none"
}
```

appmachineid

An LVM-specific derivation of /etc/machine-id is used as the system ID. See machine-id(5) to check if machine-id is available on the host.

lvm.conf

```
global {

    system_id_source = "appmachineid"
}
```

machineid

The content of /etc/machine-id is used as the system ID if available. See machine-id(5) and systemd-machine-id-setup(1) to check if machine-id is available on the host. (appmachineid is recommended in place of machineid.) lvm.conf

```
global {

    system_id_source = "machineid"
}
```

uname

The string utsname.nodename from uname(2) is used as the system ID. A uname beginning with "localhost" is ignored and equivalent to none. lvm.conf

```
global {

    system_id_source = "uname"
}
```

lvmlocal

The system ID is defined in lvmlocal.conf local/system_id. lvm.conf

```
global {

    system_id_source = "lvmlocal"
}
```

lvmlocal.conf

```
local {

    system_id = "example_name"
}
```

file

The system ID is defined in a file specified by lvm.conf global/system_id_file. lvm.conf

```
global {

    system_id_source = "file"

    system_id_file = "/path/to/file"
}
```

Changing system_id_source will likely cause the system ID of the host to change, which will prevent the host from using VGs that it previously used (see extra_system_ids below to handle this.)

If a system_id_source other than none fails to produce a system ID value, it is the equivalent of having none. The host will be allowed to access VGs with no system ID, but will not be allowed to access VGs with a system ID set.

### Overriding system ID
In some cases, it may be necessary for a host to access VGs with different system IDs, e.g. if a host's system ID changes, and it wants to use VGs that it created with its old system ID. To allow a host to access VGs with other system IDs, those other system IDs can be listed in lvmlocal.conf local/extra_system_ids.

lvmlocal.conf

```
local {

    extra_system_ids = [ "my_other_name" ]
}
```

A safer option may be configuring the extra values as needed on the command line as:

--config 'local/extra_system_ids=["id"]'

### vgcreate
In vgcreate, the host running the command assigns its own system ID to the new VG. To override this and set another system ID:

vgcreate --systemid SystemID VG PVs

Overriding the host's system ID makes it possible for a host to create a VG that it may not be able to use. Another host with a system ID matching the one specified may not recognize the new VG without manually rescanning devices.

If the --systemid argument is an empty string (""), the VG is created with no system ID, making it accessible to other hosts (see warnings above.)

### report/display
The system ID of a VG is displayed with the "systemid" reporting option.

Report/display commands ignore foreign VGs by default. To report foreign VGs, the --foreign option can be used. This causes the VGs to be read from disk.

vgs --foreign -o +systemid

When a host with no system ID sees foreign VGs, it warns about them as they are skipped. The host should be assigned a system ID, after which standard reporting commands will silently ignore foreign VGs.

### vgexport/vgimport
vgexport clears the VG system ID when exporting the VG.

vgimport sets the VG system ID to the system ID of the host doing the import.

### vgchange
A host can change the system ID of its own VGs, but the command requires confirmation because the host may lose access to the VG being changed:

vgchange --systemid SystemID VG

The system ID can be removed from a VG by specifying an empty string ("") as the new system ID. This makes the VG accessible to other hosts (see warnings above.)

A host cannot directly change the system ID of a foreign VG.

To move a VG from one host to another, vgexport and vgimport should be used.

To forcibly gain ownership of a foreign VG, a host can temporarily add the foreign system ID to its extra_system_ids list, and change the system ID of the foreign VG to its own. See Overriding system ID above.

### shared VGs
A shared VG has no system ID set, allowing multiple hosts to use it via lvmlockd. Changing a VG to shared will clear the existing system ID. Applicable only if LVM is compiled with lvmlockd support.

### clustered VGs
A clustered/clvm VG has no system ID set, allowing multiple hosts to use it via clvmd. Changing a VG to clustered will clear the existing system ID. Changing a VG to not clustered will set the system ID to the host running the vgchange command.

### creation_host
In vgcreate, the VG metadata field creation_host is set by default to the host's uname. The creation_host cannot be changed, and is not used to control access. When system_id_source is "uname", the system_id and creation_host fields will be the same.

### orphans
Orphan PVs are unused devices; they are not currently used in any VG. Because of this, they are not protected by a system ID, and any host can use them. Coordination of changes to orphan PVs is beyond the scope of system ID. The same is true of any block device that is not a PV.

## SEE ALSO
vgcreate(8), vgchange(8), vgimport(8), vgexport(8), vgs(8), lvmlockd(8), lvm.conf(5), machine-id(5), uname(2)