is a collection of performance monitoring tools for Linux including amongst others sar (collects and reports system activity) and iostat (reports CPU statistics and I/O statistics for tty devices and disks). Stable version.
| iostat.in (sysstat-12.4.0.tar.xz) | : | iostat.in (sysstat-12.4.1.tar.xz) |
|---|
| .\" iostat manual page - (C) 1998-2020 Sebastien Godard (sysstat <at> orange.fr) | | .\" iostat manual page - (C) 1998-2020 Sebastien Godard (sysstat <at> orange.fr) |
|
| .TH IOSTAT 1 "JULY 2020" Linux "Linux User's Manual" -*- nroff -*- | | .TH IOSTAT 1 "OCTOBER 2020" Linux "Linux User's Manual" -*- nroff -*- |
| .SH NAME | | .SH NAME |
| iostat \- Report Central Processing Unit (CPU) statistics and input/output | | iostat \- Report Central Processing Unit (CPU) statistics and input/output |
| statistics for devices and partitions. | | statistics for devices and partitions. |
| | |
| .SH SYNOPSIS | | .SH SYNOPSIS |
| .ie 'yes'@WITH_DEBUG@' \{ | | .ie 'yes'@WITH_DEBUG@' \{ |
| .B iostat [ -c ] [ -d ] [ -h ] [ -k | -m ] [ -N ] [ -s ] [ -t ] [ -V ] [ -x ] [
-y ] [ -z ] | | .B iostat [ -c ] [ -d ] [ -h ] [ -k | -m ] [ -N ] [ -s ] [ -t ] [ -V ] [ -x ] [
-y ] [ -z ] |
|
| .B [ --dec={ 0 | 1 | 2 } ] [ -j { ID | LABEL | PATH | UUID | ... } ] [ -o JSON ] | | .BI "[ --dec={ 0 | 1 | 2 } ] [ { -f | +f } " "directory" " ] [ -j { ID | LABEL | |
| .BI "[ [ -H ] -g " "group_name " "] [ --human ] [ --pretty ] [ -p [ " "device" " | | PATH | UUID | ... } ] " |
| [,...] | ALL ] ] [" | | .BI "[ -o JSON ] [ [ -H ] -g " "group_name " "] [ --human ] [ --pretty ] [ -p [ |
| | " "device" "[,...] | ALL ] ] [" |
| .IB "device " "[...] | ALL ] [ --debuginfo ] [ " "interval " "[ " "count " "] ]
" | | .IB "device " "[...] | ALL ] [ --debuginfo ] [ " "interval " "[ " "count " "] ]
" |
| .\} | | .\} |
| .el \{ | | .el \{ |
| .B iostat [ -c ] [ -d ] [ -h ] [ -k | -m ] [ -N ] [ -s ] [ -t ] [ -V ] [ -x ] [
-y ] [ -z ] | | .B iostat [ -c ] [ -d ] [ -h ] [ -k | -m ] [ -N ] [ -s ] [ -t ] [ -V ] [ -x ] [
-y ] [ -z ] |
|
| .B [ --dec={ 0 | 1 | 2 } ] [ -j { ID | LABEL | PATH | UUID | ... } ] [ -o JSON ] | | .BI "[ --dec={ 0 | 1 | 2 } ] [ { -f | +f } " "directory" " ] [ -j { ID | LABEL | |
| .BI "[ [ -H ] -g " "group_name " "] [ --human ] [ --pretty ] [ -p [ " "device" " | | PATH | UUID | ... } ] " |
| [,...] | ALL ] ] [" | | .BI "[ -o JSON ] [ [ -H ] -g " "group_name " "] [ --human ] [ --pretty ] [ -p [ |
| | " "device" "[,...] | ALL ] ] [" |
| .IB "device " "[...] | ALL ] [ " "interval " "[ " "count " "] ]" | | .IB "device " "[...] | ALL ] [ " "interval " "[ " "count " "] ]" |
| .\} | | .\} |
| | |
| .SH DESCRIPTION | | .SH DESCRIPTION |
| .RB "The " "iostat" | | .RB "The " "iostat" |
| command is used for monitoring system input/output device | | command is used for monitoring system input/output device |
| loading by observing the time the devices are active in relation | | loading by observing the time the devices are active in relation |
| to their average transfer rates. The | | to their average transfer rates. The |
| .B iostat | | .B iostat |
| command generates reports | | command generates reports |
| | |
| skipping to change at line 111 | | skipping to change at line 111 |
|---|
| providing that the kernel maintains statistics for it. | | providing that the kernel maintains statistics for it. |
| If the | | If the |
| .B ALL | | .B ALL |
| keyword is given on the command line, then statistics are | | keyword is given on the command line, then statistics are |
| displayed for every device defined by the system, including those | | displayed for every device defined by the system, including those |
| that have never been used. | | that have never been used. |
| Transfer rates are shown in 1K blocks by default, unless the environment | | Transfer rates are shown in 1K blocks by default, unless the environment |
| variable | | variable |
| .B POSIXLY_CORRECT | | .B POSIXLY_CORRECT |
| is set, in which case 512-byte blocks are used. | | is set, in which case 512-byte blocks are used. |
|
| The report may show the following fields, depending on the flags used: | | The report may show the following fields, depending on the flags used (e.g. |
| | .BR "-x" ", " "-s " "and " "-k " "or " "-m" "):" |
| .RS | | .RS |
| .IP Device: | | .IP Device: |
| This column gives the device (or partition) name as listed in the | | This column gives the device (or partition) name as listed in the |
| .IR "/dev " "directory." | | .IR "/dev " "directory." |
| .IP tps | | .IP tps |
| Indicate the number of transfers per second that were issued | | Indicate the number of transfers per second that were issued |
| to the device. A transfer is an I/O request to the | | to the device. A transfer is an I/O request to the |
| device. Multiple logical requests can be combined into a single I/O | | device. Multiple logical requests can be combined into a single I/O |
| request to the device. A transfer is of indeterminate size. | | request to the device. A transfer is of indeterminate size. |
| .IP "Blk_read/s (kB_read/s, MB_read/s)" | | .IP "Blk_read/s (kB_read/s, MB_read/s)" |
| Indicate the amount of data read from the device expressed in a number of | | Indicate the amount of data read from the device expressed in a number of |
| blocks (kilobytes, megabytes) per second. Blocks are equivalent to sectors | | blocks (kilobytes, megabytes) per second. Blocks are equivalent to sectors |
| and therefore have a size of 512 bytes. | | and therefore have a size of 512 bytes. |
| .IP "Blk_wrtn/s (kB_wrtn/s, MB_wrtn/s)" | | .IP "Blk_wrtn/s (kB_wrtn/s, MB_wrtn/s)" |
| Indicate the amount of data written to the device expressed in a number of | | Indicate the amount of data written to the device expressed in a number of |
| blocks (kilobytes, megabytes) per second. | | blocks (kilobytes, megabytes) per second. |
| .IP "Blk_dscd/s (kB_dscd/s, MB_dscd/s)" | | .IP "Blk_dscd/s (kB_dscd/s, MB_dscd/s)" |
| Indicate the amount of data discarded for the device expressed in a number of | | Indicate the amount of data discarded for the device expressed in a number of |
| blocks (kilobytes, megabytes) per second. | | blocks (kilobytes, megabytes) per second. |
|
| | .IP "Blk_w+d/s (kB_w+d/s, MB_w+d/s)" |
| | Indicate the amount of data written to or discarded for the device expressed |
| | in a number of blocks (kilobytes, megabytes) per second. |
| .IP "Blk_read (kB_read, MB_read)" | | .IP "Blk_read (kB_read, MB_read)" |
| The total number of blocks (kilobytes, megabytes) read. | | The total number of blocks (kilobytes, megabytes) read. |
| .IP "Blk_wrtn (kB_wrtn, MB_wrtn)" | | .IP "Blk_wrtn (kB_wrtn, MB_wrtn)" |
| The total number of blocks (kilobytes, megabytes) written. | | The total number of blocks (kilobytes, megabytes) written. |
| .IP "Blk_dscd (kB_dscd, MB_dscd)" | | .IP "Blk_dscd (kB_dscd, MB_dscd)" |
| The total number of blocks (kilobytes, megabytes) discarded. | | The total number of blocks (kilobytes, megabytes) discarded. |
|
| | .IP "Blk_w+d (kB_w+d, MB_w+d)" |
| | The total number of blocks (kilobytes, megabytes) written or discarded. |
| .IP r/s | | .IP r/s |
| The number (after merges) of read requests completed per second for the device. | | The number (after merges) of read requests completed per second for the device. |
| .IP w/s | | .IP w/s |
| The number (after merges) of write requests completed per second for the device. | | The number (after merges) of write requests completed per second for the device. |
| .IP d/s | | .IP d/s |
| The number (after merges) of discard requests completed per second for the devic
e. | | The number (after merges) of discard requests completed per second for the devic
e. |
| .IP f/s | | .IP f/s |
| The number (after merges) of flush requests completed per second for the device. | | The number (after merges) of flush requests completed per second for the device. |
| This counts flush requests executed by disks. Flush requests are not tracked for
partitions. | | This counts flush requests executed by disks. Flush requests are not tracked for
partitions. |
| Before being merged, flush operations are counted as writes. | | Before being merged, flush operations are counted as writes. |
| | |
| skipping to change at line 230 | | skipping to change at line 236 |
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| Display the device utilization report. | | Display the device utilization report. |
| .if 'yes'@WITH_DEBUG@' \{ | | .if 'yes'@WITH_DEBUG@' \{ |
| .TP | | .TP |
| .B --debuginfo | | .B --debuginfo |
| Print debug output to stderr. | | Print debug output to stderr. |
| .\} | | .\} |
| .TP | | .TP |
| .B --dec={ 0 | 1 | 2 } | | .B --dec={ 0 | 1 | 2 } |
| Specify the number of decimal places to use (0 to 2, default value is 2). | | Specify the number of decimal places to use (0 to 2, default value is 2). |
| .TP | | .TP |
|
| | .BI "-f " "directory" |
| | .RE |
| | .BI "+f " "directory" |
| | .RS |
| | Specify an alternative directory for |
| | .B iostat |
| | to read devices statistics. Option |
| | .BR "-f " "tells " "iostat " "to use only the files located in the alternative d |
| | irectory, " |
| | whereas option |
| | .B +f |
| | tells it to use both the standard kernel files and the files located in the alte |
| | rnative directory |
| | to read device statistics. |
| | |
| | .IR "directory" " is a directory containing files with statistics for devices ma |
| | naged in userspace." |
| | It may contain: |
| | |
| | - a "diskstats" file whose format is compliant with that located in "/proc", |
| | .br |
| | - statistics for individual devices contained in files whose format is compliant |
| | with that of files located in |
| | "/sys". |
| | |
| | In particular, the following files located in |
| | .I "directory" |
| | .RB "may be used by " "iostat" ":" |
| | |
| | .IR "directory" "/block/" "device" "/stat" |
| | .br |
| | .IR "directory" "/block/" "device" "/" "partition" "/stat" |
| | |
| | .IR "partition" " files must have an entry in " "directory" "/dev/block/ directo |
| | ry, e.g.:" |
| | |
| | .IR "directory" "/dev/block/" "major" ":" "minor" " --> ../../block/" "device" " |
| | /" "partition" |
| | .RE |
| | .TP |
| .BI "-g " "group_name " "{ " "device " "[...] | ALL }" | | .BI "-g " "group_name " "{ " "device " "[...] | ALL }" |
| Display statistics for a group of devices. | | Display statistics for a group of devices. |
| The | | The |
| .B iostat | | .B iostat |
| command reports statistics for each individual device in the list | | command reports statistics for each individual device in the list |
| then a line of global statistics for the group displayed as | | then a line of global statistics for the group displayed as |
| .I group_name | | .I group_name |
| and made up of all the devices in the list. The | | and made up of all the devices in the list. The |
| .B ALL | | .B ALL |
| keyword means that all the block devices defined by the system shall be | | keyword means that all the block devices defined by the system shall be |
| | | |
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