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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | COMMANDS | REGIONS, AREAS, AND GROUPS | FILE MAPPING | REPORT FIELDS | EXAMPLES | AUTHORS | SEE ALSO | COLOPHON |
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DMSTATS(8) MAINTENANCE COMMANDS DMSTATS(8)
dmstats — device-mapper statistics management
dmsetup stats command [OPTIONS]
dmstats command device_name | --major major --minor minor |
-u|--uuid uuid [-v|--verbose]
dmstats clear device_name [--allprograms|--programid id]
[--allregions|--regionid id]
dmstats create device_name...|file_path...|--alldevices [--areas
nr_areas|--areasize area_size] [--bounds
histogram_boundaries] [--filemap] [--follow follow_mode]
[--foreground] [--nomonitor] [--nogroup] [--precise]
[--start start_sector --length length|--segments]
[--userdata user_data] [--programid id]
dmstats delete device_name|--alldevices
[--allprograms|--programid id] [--allregions|--regionid
id]
dmstats group [device_name|--alldevices] [--alias name]
[--regions regions]
dmstats help [-c|-C|--columns]
dmstats list [device_name] [--histogram]
[--allprograms|--programid id] [--units units] [--area]
[--region] [--group] [--nosuffix] [--notimesuffix]
[-v|--verbose]
dmstats print [device_name] [--clear] [--allprograms|--programid
id] [--allregions|--regionid id]
dmstats report [device_name] [--interval seconds] [--count count]
[--units units] [--histogram] [--allprograms|--programid
id] [--allregions|--regionid id] [--area] [--region]
[--group] [-O|--sort sort_fields] [-S|--select selection]
[--units units] [--nosuffix] [--notimesuffix]
dmstats ungroup [device_name|--alldevices] [--groupid id]
dmstats update_filemap file_path [--groupid id] [--follow
follow_mode] [--foreground]
The dmstats program manages IO statistics regions for devices
that use the device-mapper driver. Statistics regions may be
created, deleted, listed and reported on using the tool.
The first argument to dmstats is a command.
The second argument is the device name, uuid or major and minor
numbers.
Further options permit the selection of regions, output format
control, and reporting behaviour.
When no device argument is given dmstats will by default operate
on all device-mapper devices present. The create and delete
commands require the use of --alldevices when used in this way.
--alias name
Specify an alias name for a group.
--alldevices
If no device arguments are given allow operation on all
devices when creating or deleting regions.
--allprograms
Include regions from all program IDs for list and report
operations.
--allregions
Include all present regions for commands that normally
accept a single region identifier.
--area When peforming a list or report, include objects of type
area in the results.
--areas nr_areas
Specify the number of statistics areas to create within a
new region.
--areasize area_size[b|B|s|S|k|K|m|M|g|G|t|T|p|P|e|E]
Specify the size of areas into which a new region should
be divided. An optional suffix selects units of: (b)ytes,
(s)ectors, (k)ilobytes, (m)egabytes, (g)igabytes,
(t)erabytes, (p)etabytes, (e)xabytes. Capitalise to use
multiples of 1000 (S.I.) instead of 1024.
--clear
When printing statistics counters, also atomically reset
them to zero.
--count count
Specify the iteration count for repeating reports. If the
count argument is zero reports will continue to repeat
until interrupted.
--group
When peforming a list or report, include objects of type
group in the results.
--filemap
Instead of creating regions on a device as specified by
command line options, open the file found at each
file_path argument, and create regions corresponding to
the locations of the on-disk extents allocated to the
file(s).
--nomonitor
Disable the dmfilemapd daemon when creating new file
mapped groups. Normally the device-mapper filemap
monitoring daemon, dmfilemapd, is started for each file
mapped group to update the set of regions as the file
changes on-disk: use of this option disables this
behaviour.
Regions in the group may still be updated with the
update_filemap command, or by starting the daemon
manually.
--follow follow_mode
Specify the dmfilemapd file following mode. The file map
monitoring daemon can monitor files in two distinct ways:
the mode affects the behaviour of the daemon when a file
under monitoring is renamed or unlinked, and the
conditions which cause the daemon to terminate.
The follow_mode argument is either "inode", for follow-
inode mode, or "path", for follow-path.
If follow-inode mode is used, the daemon will hold the
file open, and continue to update regions from the same
file descriptor. This means that the mapping will follow
rename, move (within the same file system), and unlink
operations. This mode is useful if the file is expected to
be moved, renamed, or unlinked while it is being
monitored.
In follow-inode mode, the daemon will exit once it detects
that the file has been unlinked and it is the last holder
of a reference to it.
If follow-path is used, the daemon will re-open the
provided path on each monitoring iteration. This means
that the group will be updated to reflect a new file being
moved to the same path as the original file. This mode is
useful for files that are expected to be updated via
unlink and rename.
In follow-path mode, the daemon will exit if the file is
removed and not replaced within a brief tolerance
interval.
In either mode, the daemon exits automatically if the
monitored group is removed.
--foreground
Specify that the dmfilemapd daemon should run in the
foreground. The daemon will not fork into the background,
and will replace the dmstats command that started it.
--groupid id
Specify the group to operate on.
--bounds histogram_boundaries[ns|us|ms|s]
Specify the boundaries of a latency histogram to be
tracked for the region as a comma separated list of
latency values. Latency values are given in nanoseconds.
An optional unit suffix of ns,us,ms, or s may be given
after each value to specify units of nanoseconds,
microseconds, miliseconds or seconds respectively.
--histogram
When used with the report and list commands select default
fields that emphasize latency histogram data.
--interval seconds
Specify the interval in seconds between successive
iterations for repeating reports. If --interval is
specified but --count is not, reports will continue to
repeat until interrupted.
--length length[b|B|s|S|k|K|m|M|g|G|t|T|p|P|e|E]
Specify the length of a new statistics region in sectors.
An optional suffix selects units of: (b)ytes, (s)ectors,
(k)ilobytes, (m)egabytes, (g)igabytes, (t)erabytes,
(p)etabytes, (e)xabytes. Capitalise to use multiples of
1000 (S.I.) instead of 1024.
-j|--major major
Specify the major number.
-m|--minor minor
Specify the minor number.
--nogroup
When creating regions mapping the extents of a file in the
file system, do not create a group or set an alias.
--nosuffix
Suppress the suffix on output sizes. Use with --units
(except h and H) if processing the output.
--notimesuffix
Suppress the suffix on output time values. Histogram
boundary values will be reported in units of nanoseconds.
-o|--options
Specify which report fields to display.
-O|--sort sort_fields
Sort output according to the list of fields given. Precede
any sort field with '-' for a reverse sort on that column.
--precise
Attempt to use nanosecond precision counters when creating
new statistics regions.
--programid id
Specify a program ID string. When creating new statistics
regions this string is stored with the region. Subsequent
operations may supply a program ID in order to select only
regions with a matching value. The default program ID for
dmstats-managed regions is "dmstats".
--region
When peforming a list or report, include objects of type
region in the results.
--regionid id
Specify the region to operate on.
--regions region_list
Specify a list of regions to group. The group list is a
comma-separated list of region identifiers. Continuous
sequences of identifiers may be expressed as a hyphen
separated range, for example: '1-10'.
--relative
If displaying the histogram report show relative
(percentage) values instead of absolute counts.
-S|--select selection
Display only rows that match selection criteria. All rows
with the additional "selected" column (-o selected)
showing 1 if the row matches the selection and 0
otherwise. The selection criteria are defined by
specifying column names and their valid values while
making use of supported comparison operators.
--start start[b|B|s|S|k|K|m|M|g|G|t|T|p|P|e|E]
Specify the start offset of a new statistics region in
sectors. An optional suffix selects units of: (b)ytes,
(s)ectors, (k)ilobytes, (m)egabytes, (g)igabytes,
(t)erabytes, (p)etabytes, (e)xabytes. Capitalise to use
multiples of 1000 (S.I.) instead of 1024.
--segments
When used with create, create a new statistics region for
each target contained in the given device(s). This causes
a separate region to be allocated for each segment of the
device.
The newly created regions are automatically placed into a
group unless the --nogroup option is given. When grouping
is enabled a group alias may be specified using the
--alias option.
--units [units][h|H|b|B|s|S|k|K|m|M|g|G|t|T|p|P|e|E]
Set the display units for report output. All sizes are
output in these units: (h)uman-readable, (b)ytes,
(s)ectors, (k)ilobytes, (m)egabytes, (g)igabytes,
(t)erabytes, (p)etabytes, (e)xabytes. Capitalise to use
multiples of 1000 (S.I.) instead of 1024. Can also
specify custom units e.g. --units 3M.
--userdata user_data
Specify user data (a word) to be stored with a new region.
The value is added to any internal auxiliary data (for
example, group information), and stored with the region in
the aux_data field provided by the kernel. Whitespace is
not permitted.
-u|--uuid
Specify the uuid.
-v|--verbose [-v|--verbose]
Produce additional output.
clear device_name [--allprograms|--programid id]
[--allregions|--regionid id]
Instructs the kernel to clear statistics counters for the
speficied regions (with the exception of in-flight IO
counters).
create device_name...|file_path...|--alldevices [--areas
nr_areas|--areasize area_size] [--bounds
histogram_boundaries] [--filemap] [--follow follow_mode]
[--foreground] [--nomonitor] [--nogroup] [--precise]
[--start start_sector --length length|--segments]
[--userdata user_data] [--programid id]
Creates one or more new statistics regions on the
specified device(s).
The region will span the entire device unless --start and
--length or --segments are given. The --start an --length
options allow a region of arbitrary length to be placed at
an arbitrary offset into the device. The --segments option
causes a new region to be created for each target in the
corresponding device-mapper device's table.
If the --precise option is used the command will attempt
to create a region using nanosecond precision counters.
If --bounds is given a latency histogram will be tracked
for the new region. The boundaries of the histogram bins
are given as a comma separated list of latency values.
There is an implicit lower bound of zero on the first bin
and an implicit upper bound of infinity (or the configured
interval duration) on the final bin.
Latencies are given in nanoseconds. An optional unit
suffix of ns, us, ms, or s may be given after each value
to specify units of nanoseconds, microseconds, miliseconds
or seconds respectively, so for example, 10ms is
equivalent to 10000000. Latency values with a precision of
less than one milisecond can only be used when precise
timestamps are enabled: if --precise is not given and
values less than one milisecond are used it will be
enabled automatically.
An optional program_id or user_data string may be
associated with the region. A program_id may then be used
to select regions for subsequent list, print, and report
operations. The user_data stores an arbitrary string and
is not used by dmstats or the device-mapper kernel
statistics subsystem.
By default dmstats creates regions with a program_id of
"dmstats".
On success the region_id of the newly created region is
printed to stdout.
If the --filemap option is given with a regular file, or
list of files, as the file_path argument, instead of
creating regions with parameters specified on the command
line, dmstats will open the files located at file_path and
create regions corresponding to the physical extents
allocated to the file. This can be used to monitor
statistics for individual files in the file system, for
example, virtual machine images, swap areas, or large
database files.
To work with the --filemap option, files must be located
on a local file system, backed by a device-mapper device,
that supports physical extent data using the FIEMAP ioctl
(Ext4 and XFS for e.g.).
By default regions that map a file are placed into a group
and the group alias is set to the basename of the file.
This behaviour can be overridden with the --alias and
--nogroup options.
Creating a group that maps a file automatically starts a
daemon, dmfilemapd to monitor the file and update the
mapping as the extents allocated to the file change. This
behaviour can be disabled using the --nomonitor option.
Use the --group option to only display information for
groups when listing and reporting.
delete device_name|--alldevices [--allprograms|--programid id]
[--allregions|--regionid id]
Delete the specified statistics region. All counters and
resources used by the region are released and the region
will not appear in the output of subsequent list, print,
or report operations.
All regions registered on a device may be removed using
--allregions.
To remove all regions on all devices both --allregions and
--alldevices must be used.
If a --groupid is given instead of a --regionid the
command will attempt to delete the group and all regions
that it contains.
If a deleted region is the first member of a group of
regions the group will also be removed.
group [device_name|--alldevices] [--alias name] [--regions
regions]
Combine one or more statistics regions on the specified
device into a group.
The list of regions to be grouped is specified with
--regions and an optional alias may be assigned with
--alias. The set of regions is given as a comma-separated
list of region identifiers. A continuous range of
identifers spanning from R1 to R2 may be expressed as
'R1-R2'.
Regions that have a histogram configured can be grouped:
in this case the number of histogram bins and their bounds
must match exactly.
On success the group list and newly created group_id are
printed to stdout.
The group metadata is stored with the first (lowest
numbered) region_id in the group: deleting this region
will also delete the group and other group members will be
returned to their prior state.
help [-c|-C|--columns]
Outputs a summary of the commands available, optionally
including the list of report fields.
list [device_name] [--histogram] [--allprograms|--programid id]
[--units units] [--area] [--region] [--group] [--nosuffix]
[--notimesuffix] [-v|--verbose]
List the statistics regions, areas, or groups registered
on the device. If the --allprograms switch is given all
regions will be listed regardless of region program ID
values.
By default only regions and groups are included in list
output. If -v or --verbose is given the report will also
include a row of information for each configured group and
for each area contained in each region displayed.
Regions that contain a single area are by default omitted
from the verbose list since their properties are identical
to the area that they contain - to view all regions
regardless of the number of areas present use --region).
To also view the areas contained within regions use
--area.
If --histogram is given the report will include the bin
count and latency boundary values for any configured
histograms.
print [device_name] [--clear] [--allprograms|--programid id]
[--allregions|--regionid id]
Print raw statistics counters for the specified region or
for all present regions.
report [device_name] [--interval seconds] [--count count]
[--units units] [--histogram] [--allprograms|--programid
id] [--allregions|--regionid id] [--area] [--region]
[--group] [-O|--sort sort_fields] [-S|--select selection]
[--units units] [--nosuffix] [--notimesuffix]
Start a report for the specified object or for all present
objects. If the count argument is specified, the report
will repeat at a fixed interval set by the --interval
option. The default interval is one second.
If the --allprograms switch is given, all regions will be
listed, regardless of region program ID values.
If the --histogram is given the report will include the
histogram values and latency boundaries.
If the --relative is used the default histogram field
displays bin values as a percentage of the total number of
I/Os.
Object types (areas, regions and groups) to include in the
report are selected using the --area, --region, and
--group options.
ungroup [device_name|--alldevices] [--groupid id]
Remove an existing group and return all the group's
regions to their original state.
The group to be removed is specified using --groupid.
update_filemap file_path [--groupid id] [--follow follow_mode]
[--foreground]
Update a group of dmstats regions specified by group_id,
that were previously created with --filemap, either
directly, or by starting the monitoring daemon,
dmfilemapd.
This will add and remove regions to reflect changes in the
allocated extents of the file on-disk, since the time that
it was crated or last updated.
Use of this command is not normally needed since the
dmfilemapd daemon will automatically monitor filemap
groups and perform these updates when required.
If a filemapped group was created with --nomonitor, or the
daemon has been killed, the update_filemap can be used to
manually force an update or start a new daemon.
Use --nomonitor to force a direct update and disable
starting the monitoring daemon.
The device-mapper statistics facility allows separate performance
counters to be maintained for arbitrary regions of devices. A
region may span any range: from a single sector to the whole
device. A region may be further sub-divided into a number of
distinct areas (one or more), each with its own counter set. In
this case a summary value for the entire region is also available
for use in reports.
In addition, one or more regions on one device can be combined
into a statistics group. Groups allow several regions to be
aggregated and reported as a single entity; counters for all
regions and areas are summed and used to report totals for all
group members. Groups also permit the assignment of an optional
alias, allowing meaningful names to be associated with sets of
regions.
The group metadata is stored with the first (lowest numbered)
region_id in the group: deleting this region will also delete the
group and other group members will be returned to their prior
state.
By default new regions span the entire device. The --start and
--length options allows a region of any size to be placed at any
location on the device.
Using offsets it is possible to create regions that map
individual objects within a block device (for example:
partitions, files in a file system, or stripes or other
structures in a RAID volume). Groups allow several non-contiguous
regions to be assembled together for reporting and data
aggregation.
A region may be either divided into the specified number of
equal-sized areas, or into areas of the given size by specifying
one of --areas or --areasize when creating a region with the
create command. Depending on the size of the areas and the device
region the final area within the region may be smaller than
requested.
Region identifiers
Each region is assigned an identifier when it is created that is
used to reference the region in subsequent operations. Region
identifiers are unique within a given device (including across
different program_id values).
Depending on the sequence of create and delete operations, gaps
may exist in the sequence of region_id values for a particular
device.
The region_id should be treated as an opaque identifier used to
reference the region.
Group identifiers
Groups are also assigned an integer identifier at creation time;
like region identifiers, group identifiers are unique within the
containing device.
The group_id should be treated as an opaque identifier used to
reference the group.
Using --filemap, it is possible to create regions that correspond
to the extents of a file in the file system. This allows IO
statistics to be monitored on a per-file basis, for example to
observe large database files, virtual machine images, or other
files of interest.
To be able to use file mapping, the file must be backed by a
device-mapper device, and in a file system that supports the
FIEMAP ioctl (and which returns data describing the physical
location of extents). This currently includes xfs(5) and ext4(5).
By default the regions making up a file are placed together in a
group, and the group alias is set to the basename(3) of the file.
This allows statistics to be reported for the file as a whole,
aggregating values for the regions making up the group. To see
only the whole file (group) when using the list and report
commands, use --group.
Since it is possible for the file to change after the initial
group of regions is created, the update_filemap command, and
dmfilemapd daemon are provided to update file mapped groups
either manually or automatically.
File follow modes
The file map monitoring daemon can monitor files in two distinct
ways: follow-inode mode, and follow-path mode.
The mode affects the behaviour of the daemon when a file under
monitoring is renamed or unlinked, and the conditions which cause
the daemon to terminate.
If follow-inode mode is used, the daemon will hold the file open,
and continue to update regions from the same file descriptor.
This means that the mapping will follow rename, move (within the
same file system), and unlink operations. This mode is useful if
the file is expected to be moved, renamed, or unlinked while it
is being monitored.
In follow-inode mode, the daemon will exit once it detects that
the file has been unlinked and it is the last holder of a
reference to it.
If follow-path is used, the daemon will re-open the provided path
on each monitoring iteration. This means that the group will be
updated to reflect a new file being moved to the same path as the
original file. This mode is useful for files that are expected to
be updated via unlink and rename.
In follow-path mode, the daemon will exit if the file is removed
and not replaced within a brief tolerance interval (one second).
To stop the daemon, delete the group containing the mapped
regions: the daemon will automatically shut down.
The daemon can also be safely killed at any time and the group
kept: if the file is still being allocated the mapping will
become progressively out-of-date as extents are added and removed
(in this case the daemon can be re-started or the group updated
manually with the update_filemap command).
See the create command and --filemap, --follow, and --nomonitor
options for further information.
Limitations
The daemon attempts to maintain good synchronisation between the
file extents and the regions contained in the group, however,
since it can only react to new allocations once they have been
written, there are inevitably some IO events that cannot be
counted when a file is growing, particularly if the file is being
extended by a single thread writing beyond end-of-file (for
example, the dd program).
There is a further loss of events in that there is currently no
way to atomically resize a dmstats region and preserve its
current counter values. This affects files when they grow by
extending the final extent, rather than allocating a new extent:
any events that had accumulated in the region between any prior
operation and the resize are lost.
File mapping is currently most effective in cases where the
majority of IO does not trigger extent allocation. Future updates
may address these limitations when kernel support is available.
The dmstats report provides several types of field that may be
added to the default field set, or used to create custom reports.
All performance counters and metrics are calculated per-area.
Derived metrics
A number of metrics fields are included that provide high level
performance indicators. These are based on the fields provided by
the conventional Linux iostat program and are derived from the
basic counter values provided by the kernel for each area.
reads_merged_per_sec
Reads merged per second.
writes_merged_per_sec
Writes merged per second.
reads_per_sec
Reads completed per second.
writes_per_sec
Writes completed per second.
read_size_per_sec
Size of data read per second.
write_size_per_sec
Size of data written per second.
avg_request_size
Average request size.
queue_size
Average queue size.
await The average wait time for read and write operations.
r_await
The average wait time for read operations.
w_await
The average wait time for write operations.
throughput
The device throughput in operations per second.
service_time
The average service time (in milliseconds) for operations
issued to the device.
util Percentage of CPU time during which I/O requests were
issued to the device (bandwidth utilization for the
device). Device saturation occurs when this value is close
to 100%.
Group, region and area meta fields
Meta fields provide information about the groups, regions, or
areas that the statistics values relate to. This includes the
region and area identifier, start, length, and counts, as well as
the program ID and user data values.
region_id
Region identifier. This is a non-negative integer returned
by the kernel when a statistics region is created.
region_start
The region start location. Display units are selected by
the --units option.
region_len
The length of the region. Display units are selected by
the --units option.
area_id
Area identifier. Area identifiers are assigned by the
device-mapper statistics library and uniquely identify
each area within a region. Each ID corresponds to a
distinct set of performance counters for that area of the
statistics region. Area identifiers are always
monotonically increasing within a region so that higher ID
values correspond to greater sector addresses within the
area and no gaps in the sequence of identifiers exist.
area_start
The area start location. Display units are selected by the
--units option.
area_len
The length of the area. Display units are selected by the
--units option.
area_count
The number of areas in this region.
program_id
The program ID value associated with this region.
user_data
The user data value associated with this region.
group_id
Group identifier. This is a non-negative integer returned
by the dmstats group command when a statistics group is
created.
interval_ns
The estimated interval over which the current counter
values have accumulated. The value is reported as an
integer expressed in units of nanoseconds.
interval
The estimated interval over which the current counter
values have accumulated. The value is reported as a real
number in units of seconds.
Basic counters
Basic counters provide access to the raw counter data from the
kernel, allowing further processing to be carried out by another
program.
The kernel provides thirteen separate counters for each
statistics area. The first eleven of these match the counters
provided in /proc/diskstats or /sys/block/*/*/stat. The final
pair provide separate counters for read and write time.
read_count
Count of reads completed this interval.
reads_merged_count
Count of reads merged this interval.
read_sector_count
Count of 512 byte sectors read this interval.
read_time
Accumulated duration of all read requests (ns).
write_count
Count of writes completed this interval.
writes_merged_count
Count of writes merged this interval.
write_sector_count
Count of 512 byte sectors written this interval.
write_time
Accumulated duration of all write requests (ns).
in_progress_count
Count of requests currently in progress.
io_ticks
Nanoseconds spent servicing requests.
queue_ticks
This field is incremented at each I/O start, I/O
completion, I/O merge, or read of these stats by the
number of I/Os in progress multiplied by the number of
milliseconds spent doing I/O since the last update of this
field. This can provide an easy measure of both I/O
completion time and the backlog that may be accumulating.
read_ticks
Nanoseconds spent servicing reads.
write_ticks
Nanoseconds spent servicing writes.
Histogram fields
Histograms measure the frequency distribution of user specified
I/O latency intervals. Histogram bin boundaries are specified
when a region is created.
A brief representation of the histogram values and latency
intervals can be included in the report using these fields.
hist_count
A list of the histogram counts for the current statistics
area in order of ascending latency value. Each value
represents the number of I/Os with latency times falling
into that bin's time range during the sample period.
hist_count_bounds
A list of the histogram counts for the current statistics
area in order of ascending latency value including bin
boundaries: each count is prefixed by the lower bound of
the corresponding histogram bin.
hist_count_ranges
A list of the histogram counts for the current statistics
area in order of ascending latency value including bin
boundaries: each count is prefixed by both the lower and
upper bounds of the corresponding histogram bin.
hist_percent
A list of the relative histogram values for the current
statistics area in order of ascending latency value,
expressed as a percentage. Each value represents the
proportion of I/Os with latency times falling into that
bin's time range during the sample period.
hist_percent_bounds
A list of the relative histogram values for the current
statistics area in order of ascending latency value,
expressed as a percentage and including bin boundaries.
Each value represents the proportion of I/Os with latency
times falling into that bin's time range during the sample
period and is prefixed with the corresponding bin's lower
bound.
hist_percent_ranges
A list of the relative histogram values for the current
statistics area in order of ascending latency value,
expressed as a percentage and including bin boundaries.
Each value represents the proportion of I/Os with latency
times falling into that bin's time range during the sample
period and is prefixed with the corresponding bin's lower
and upper bounds.
hist_bounds
A list of the histogram boundary values for the current
statistics area in order of ascending latency value. The
values are expressed in whole units of seconds,
miliseconds, microseconds or nanoseconds with a suffix
indicating the unit.
hist_ranges
A list of the histogram bin ranges for the current
statistics area in order of ascending latency value. The
values are expressed as "LOWER-UPPER" in whole units of
seconds, miliseconds, microseconds or nanoseconds with a
suffix indicating the unit.
hist_bins
The number of latency histogram bins configured for the
area.
Create a whole-device region with one area on vg00/lvol1
# dmstats create vg00/lvol1
vg00/lvol1: Created new region with 1 area(s) as region ID 0
Create a 32M region 1G into device d0
# dmstats create --start 1G --length 32M d0
d0: Created new region with 1 area(s) as region ID 0
Create a whole-device region with 8 areas on every device
# dmstats create --areas 8
vg00-lvol1: Created new region with 8 area(s) as region ID 0
vg00-lvol2: Created new region with 8 area(s) as region ID 0
vg00-lvol3: Created new region with 8 area(s) as region ID 0
vg01-lvol0: Created new region with 8 area(s) as region ID 2
vg01-lvol1: Created new region with 8 area(s) as region ID 0
vg00-lvol2: Created new region with 8 area(s) as region ID 1
Delete all regions on all devices
# dmstats delete --alldevices --allregions
Create a whole-device region with areas 10GiB in size on
vg00/lvol1 using dmsetup
# dmsetup stats create --areasize 10G vg00/lvol1
vg00-lvol1: Created new region with 5 area(s) as region ID 1
Create a 1GiB region with 16 areas at the start of vg00/lvol1
# dmstats create --start 0 --len 1G --areas=16 vg00/lvol1
vg00-lvol1: Created new region with 16 area(s) as region ID 0
List the statistics regions registered on vg00/lvol1
# dmstats list vg00/lvol1
Name RgID RStart RSize #Areas ASize ProgID
vg00-lvol1 0 0 61.00g 1 61.00g dmstats
vg00-lvol1 1 61.00g 19.20g 1 19.20g dmstats
vg00-lvol1 2 80.20g 2.14g 1 2.14g dmstats
Display five statistics reports for vg00/lvol1 at an interval of
one second
# dmstats report --interval 1 --count 5 vg00/lvol1
# dmstats report
Name RgID ArID AStart ASize RRqM/s WRqM/s R/s
W/s RSz/s WSz/s AvRqSz QSize Util% AWait RdAWa WrAWa
vg_hex-lv_home 0 0 0 61.00g 0.00 0.00
0.00 218.00 0 1.04m 4.50k 2.97 81.70 13.62 0.00
13.62
vg_hex-lv_home 1 0 61.00g 19.20g 0.00 0.00
0.00 5.00 0 548.00k 109.50k 0.14 11.00 27.40 0.00
27.40
vg_hex-lv_home 2 0 80.20g 2.14g 0.00 0.00
0.00 14.00 0 1.15m 84.00k 0.39 18.70 27.71 0.00
27.71
Create one region for reach target contained in device vg00/lvol1
# dmstats create --segments vg00/lvol1
vg00-lvol1: Created new region with 1 area(s) as region ID 0
vg00-lvol1: Created new region with 1 area(s) as region ID 1
vg00-lvol1: Created new region with 1 area(s) as region ID 2
Create regions mapping each file in the directory images/ and
place them into separate groups, each named after the
corresponding file
# dmstats create --filemap images/*
images/vm1.qcow2: Created new group with 87 region(s) as group ID
0.
images/vm1-1.qcow2: Created new group with 8 region(s) as group
ID 87.
images/vm2.qcow2: Created new group with 11 region(s) as group ID
95.
images/vm2-1.qcow2: Created new group with 1454 region(s) as
group ID 106.
images/vm3.img: Created new group with 2 region(s) as group ID
1560.
Print raw counters for region 4 on device d0
# dmstats print --regionid 4 d0
2097152+65536 0 0 0 0 29 0 264 701 0 41 701 0 41
Bryn M. Reeves <bmr@redhat.com>
dmsetup(8)
LVM2 resource page: ⟨https://www.sourceware.org/lvm2⟩
Device-mapper resource page: ⟨http://sources.redhat.com/dm⟩
Device-mapper statistics kernel documentation
Documentation/device-mapper/statistics.txt
This page is part of the lvm2 (Logical Volume Manager 2) project.
Information about the project can be found at
⟨http://www.sourceware.org/lvm2/⟩. If you have a bug report for
this manual page, see ⟨https://github.com/lvmteam/lvm2/issues⟩.
This page was obtained from the project's upstream Git repository
⟨git://sourceware.org/git/lvm2.git⟩ on 2022-12-17. (At that
time, the date of the most recent commit that was found in the
repository was 2022-12-15.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Linux Jun 23 2016 DMSTATS(8)
Pages that refer to this page: pmdadm(1), dmfilemapd(8), dmsetup(8), lvm(8), lvmsadc(8), lvmsar(8)
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