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.

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

Sorting

Selection

Changing output format and composition

Special options

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):

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:

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. To see unfiltered command log, use "all" value for the selection. 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:

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):

Message (mandatory):

Object information (used only if applicable):

Numeric status (used only if applicable):

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

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:

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

"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).

•

Freeform time format

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).

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 configuration 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

In certain cases, you may find it more useful to report full column names instead of abbreviated column names in report headings. To do this, use report/headings=2 configuration setting (or --headings full or --headings 2 command line option). The full column names are the exact names that you also use in FieldSet for -o|--options. These names are unambiguous, without spaces (one word only) and they also make it easier to match the output with requested FieldSet:

# lvs -o+seg_start,seg_start_pe


  LV    VG LSize Cpy%Sync Start Start


  lvol0 vg 4.00m             0      0


  lvol1 vg 4.00m 100.00      0      0
# lvs --headings full -o+seg_start,seg_start_pe


  lv_name vg_name lv_size copy_percent seg_start seg_start_pe


  lvol0   vg        4.00m                     0             0


  lvol1   vg        4.00m 100.00              0             0

Changing output format¶

LVM can output reports in different formats - use report/output_format configuration setting (or --reportformat command line option) to switch the report output format.

Currently, LVM supports these output formats:

For example:

# lvs -o lv_name,lv_size --reportformat json


  {


      "report": [


          {


              "lv": [


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


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


              ]


          }


      ]


  }

The json_std output format is more compliant with JSON standard and compared to the original json format:

Note that some configuration settings and command line options have no effect with certain report formats. For example, with json or json_std 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 or json_std 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