iostat (iostat命令報告CPU和I/O使用情況統計信息)

瑞茲發表于 2021-01-26 09:10

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命令行 Unix&Linux命令 iostat

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在類似Unix的操作系統上，iostat命令報告CPU和I/O使用情況統計信息。

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1 iostat 運行系統環境

2 iostat 描述

3 iostat 語法

4 iostat 例子

iostat 運行系統環境

Unix&Linux

iostat 描述

所述的iostat命令用于通過觀察時間的裝置在相對于它們的平均傳輸速率監測活性系統的輸入/輸出設備負載。所述的iostat命令生成可用于改變系統報告配置，以更好地平衡物理之間的輸入/輸出負荷的磁盤。

iostat命令生成的第一個報告提供有關自系統啟動以來的時間的統計信息。每個后續報告涵蓋自上一個報告以來的時間。每次運行iostat命令時，都會報告所有統計信息。該報告由一個CPU標頭行和隨后的CPU統計信息行組成。在多處理器系統上，CPU統計信息是系統范圍內所有處理器的平均值。將顯示設備標題行，后跟配置的每個設備的一行統計信息。

interval參數指定每個報告之間的時間間隔（以秒為單位）。第一個報告包含自系統啟動（引導）以來的時間統計信息。每個后續報告均包含自上次報告以來的時間間隔內收集的統計信息。所述計數參數可以與結合指定間隔參數。如果指定了count參數，count的值將確定間隔間隔秒生成的報告數。如果間隔沒有被指定的參數計數參數，所述的iostat命令連續地生成報告。

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iostat 語法

iostat [ -c ] [ -d ] [ -h ] [ -N ] [ -k | -m ] [ -t ] [ -V ] [ -x ]
       [ -z ] [ [ [ -T ] -g group_name ] { device [...] | ALL } ]
       [ -p [ device [,...] | ALL ] ] [ interval [ count ] ]

報告書

該iostat的命令生成三種類型的報告：CPU使用率報告，該設備利用率報告和網絡文件系統的報告。

CPU使用率報告

iostat命令生成的第一個報告是CPU利用率報告。對于多處理器系統，CPU值是所有處理器之間的全局平均值。該報告具有以下格式：

％user	顯示在用戶（應用程序）級別執行時發生的CPU利用率百分比。
％nice	顯示具有良好優先級的用戶級別執行時發生的CPU利用率百分比。
％system	顯示在系統（內核）級別執行時發生的CPU利用率百分比。
％iowait	顯示在系統有未完成的磁盤I / O請求期間，一個或多個CPU空閑的時間百分比。
％steal	顯示在管理程序為另一個虛擬處理器提供服務時，一個或多個虛擬CPU在非自愿等待中花費的時間百分比。
％idle	顯示一個或多個CPU空閑且系統沒有未完成的磁盤I / O請求的時間百分比。

設備使用率報告

iostat命令生成的第二個報告是“設備使用率報告”。設備報告提供了基于每個物理設備或分區的統計信息。可以在命令行上輸入要顯示其統計信息的塊設備和分區。如果未輸入設備或分區，則將顯示系統使用的每個設備的統計信息，前提是內核需要為其維護統計信息。

如果在命令行上指定了ALL 關鍵字，則將顯示系統定義的每個設備的統計信息，包括從未使用過的設備。除非設置了環境變量 POSIXLY_CORRECT，否則默認情況下傳輸速率以1K塊為單位，在這種情況下，將使用512字節的塊。該報告可能顯示以下字段，具體取決于所使用的標志：

Device	此列提供/ dev目錄中列出的設備（或分區）名稱。
tps	指示每秒發送到設備的傳輸次數。傳輸是對設備的I / O請求。多個邏輯請求可以組合成對設備的單個I / O請求。傳輸的大小不確定。
Blk_read / s（kB_read / s，MB_read / s）	表示從設備讀取的數據量，以每秒的塊數（千字節，兆字節）表示。塊等同于扇區，因此大小為512字節。
Blk_wrtn / s（kB_wrtn / s，MB_wrtn / s）	指示寫入設備的數據量，以每秒的塊數（千字節，兆字節）表示。
Blk_read（kB_read，MB_read）	讀取的總塊數（千字節，兆字節）。
Blk_wrtn（kB_wrtn，MB_wrtn）	寫入的總塊數（千字節，兆字節）。
rrqm /s	每秒排隊到設備中的讀取請求的數量。
wrqm /s	每秒排隊到設備中的合并寫入請求的數量。
r /s	每秒設備完成的讀取請求數（合并后）。
w / s	每秒設備完成的寫請求數（合并后）。
rsec / s（rkB / s，rMB / s）	每秒從設備讀取的扇區數（千字節，兆字節）。
wsec / s（wkB / s，wMB / s）	每秒寫入設備的扇區數（千字節，兆字節）。
avgrq-sz	發出到設備的請求的平均大小（以扇區為單位）。
avgqu-sz	發出到設備的請求的平均隊列長度。
r_await	發出給要服務的設備的I / O請求的平均時間（以毫秒為單位）。這包括隊列中的請求所花費的時間以及為請求服務所花費的時間。
r_await	發送給要服務的設備的讀取請求的平均時間（以毫秒為單位）。這包括隊列中的請求所花費的時間以及為請求服務所花費的時間。
w_await	發出要服務的設備的寫請求的平均時間（以毫秒為單位）。這包括隊列中的請求所花費的時間以及為請求服務所花費的時間。
svctm	發出給設備的I / O請求的平均服務時間（以毫秒為單位）。警告！不再相信這個領域！將來的sysstat版本中將刪除此字段。
％util	向設備發出I / O請求的CPU時間百分比（設備的帶寬利用率）。當該值接近100％時，發生器件飽和。

選件

-C	顯示CPU利用率報告。
-d	顯示設備利用率報告。
-g group_name {device[...] \| ALL}	顯示一組設備的統計信息。所述的iostat為列表中的每個設備命令報告統計，然后該組全局統計的線顯示為組名由列表中的所有設備的向上。該ALL關鍵字意味著，所有由系統定義塊裝置應被包括在組中。
-H	使設備使用情況報告更易于人閱讀。（那是你！）
-k	顯示統計信息（以千字節/秒為單位）。
-m	顯示統計信息，以每秒兆字節為單位。
-N	顯示任何設備映射器設備的注冊設備映射器名稱。用于查看LVM2統計信息。
-p [{devicce[ ， ...] \| ALL}]	該-p選項顯示的統計數據塊設備和由該系統所使用的所有的分區。如果在命令行上輸入了設備名稱，則將顯示該設備及其所有分區的統計信息。該ALL關鍵字表示統計必須顯示對于所有的塊設備和分區由系統定義的，包括那些從未使用過。
-T	此選項必須與選項-g一起使用，并指示僅顯示該組的全局統計信息，而不顯示該組中各個設備的統計信息。
-t	打印顯示的每個報告的時間。時間戳格式可能取決于S_TIME_FORMAT環境變量的值（請參見下文）。
-V	打印版本號并退出。
-X	顯示擴展統計信息。
-z	告訴iostat忽略在采樣期間沒有任何活動的任何設備的輸出。

環境

該iostat的命令考慮到了以下環境變量：

S_TIME_FORMAT	如果此變量存在且其值為ISO，則在報表標題中打印日期時，將忽略當前語言環境。該iostat的命令將使用ISO 8601格式（YYYY - MM - DD）來代替。選項-t所顯示的時間戳也將符合ISO 8601格式。
POSIXLY_CORRECT	設置此變量后，傳輸速率將以512-K塊而不是默認的1K塊顯示。

iostat [ -c ] [ -d ] [ -h ] [ -N ] [ -k | -m ] [ -t ] [ -V ] [ -x ]
       [ -z ] [ [ [ -T ] -g group_name ] { device [...] | ALL } ]
       [ -p [ device [,...] | ALL ] ] [ interval [ count ] ]

Reports

The iostat command generates three types of reports: the CPU Utilization report, the Device Utilization report and the Network Filesystem report.

CPU Utilization Report

The first report generated by the iostat command is the CPU Utilization Report. For multiprocessor systems, the CPU values are global averages among all processors. The report has the following format:

%user	Show the percentage of CPU utilization that occurred while executing at the user (application) level.
%nice	Show the percentage of CPU utilization that occurred while executing at the user level with nice priority.
%system	Show the percentage of CPU utilization that occurred while executing at the system (kernel) level.
%iowait	Show the percentage of time that the CPU or CPUs were idle during which the system had an outstanding disk I/O request.
%steal	Show the percentage of time spent in involuntary wait by the virtual CPU or CPUs while the hypervisor was servicing another virtual processor.
%idle	Show the percentage of time that the CPU or CPUs were idle and the system did not have an outstanding disk I/O request.

Device Utilization Report

The second report generated by the iostat command is the Device Utilization Report. The device report provides statistics on a per-physical device or partition basis. Block devices and partitions for which statistics are to be displayed may be entered on the command line. If no device nor partition is entered, then statistics are displayed for every device used by the system, providing that the kernel maintains statistics for it.

If the ALL keyword is given on the command line, then statistics are displayed for every device defined by the system, including those that have never been used. Transfer rates are shown in 1K blocks by default, unless the environment variable POSIXLY_CORRECT is set, in which case 512-byte blocks are used. The report may show the following fields, depending on the flags used:

Device	This column gives the device (or partition) name as listed in the /dev directory.
tps	Indicate the number of transfers per second that were issued to the device. A transfer is an I/O request to the device. Multiple logical requests can be combined into a single I/O request to the device. A transfer is of indeterminate size.
Blk_read/s (kB_read/s, MB_read/s)	Indicate the amount of data read from the device expressed in a number of blocks (kilobytes, megabytes) per second. Blocks are equivalent to sectors and therefore have a size of 512 bytes.
Blk_wrtn/s (kB_wrtn/s, MB_wrtn/s)	Indicate the amount of data written to the device expressed in a number of blocks (kilobytes, megabytes) per second.
Blk_read (kB_read, MB_read)	The total number of blocks (kilobytes, megabytes) read.
Blk_wrtn (kB_wrtn, MB_wrtn)	The total number of blocks (kilobytes, megabytes) written.
rrqm/s	The number of read requests merged per second that were queued to the device.
wrqm/s	The number of write requests merged per second that were queued to the device.
r/s	The number (after merges) of read requests completed per second for the device.
w/s	The number (after merges) of write requests completed per second for the device.
rsec/s (rkB/s, rMB/s)	The number of sectors (kilobytes, megabytes) read from the device per second.
wsec/s (wkB/s, wMB/s)	The number of sectors (kilobytes, megabytes) written to the device per second.
avgrq-sz	The average size (in sectors) of the requests that were issued to the device.
avgqu-sz	The average queue length of the requests that were issued to the device.
await	The average time (in milliseconds) for I/O requests issued to the device to be served. This includes the time spent by the requests in queue and the time spent servicing them.
r_await	The average time (in milliseconds) for read requests issued to the device to be served. This includes the time spent by the requests in queue and the time spent servicing them.
w_await	The average time (in milliseconds) for write requests issued to the device to be served. This includes the time spent by the requests in queue and the time spent servicing them.
svctm	The average service time (in milliseconds) for I/O requests that were issued to the device. Warning! Do not trust this field anymore! This field will be removed in a future sysstat version.
%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%.

Options

-c	Display the CPU utilization report.
-d	Display the device utilization report.
-g group_name { device [...] \| ALL }	Display statistics for a group of devices. The iostat command reports statistics for each device in the list, then a line of global statistics for the group displayed as group_name made up of all the devices in the list. The ALL keyword means that all the block devices defined by the system shall be included in the group.
-h	Make the Device Utilization Report easier to read by a human. (That's you!)
-k	Display statistics in kilobytes per second.
-m	Display statistics in megabytes per second.
-N	Display the registered device mapper names for any device mapper devices. Useful for viewing LVM2 statistics.
-p [ { device [,...] \| ALL } ]	The -p option displays statistics for block devices and all their partitions that are used by the system. If a device name is entered on the command line, then statistics for it and all its partitions are displayed. The ALL keyword indicates that statistics have to be displayed for all the block devices and partitions defined by the system, including those that have never been used.
-T	This option must be used with option -g and indicates that only global statistics for the group are to be displayed, and not statistics for individual devices in the group.
-t	Print the time for each report displayed. The timestamp format may depend on the value of the S_TIME_FORMAT environment variable (see below).
-V	Print version number and exit.
-x	Display extended statistics.
-z	Tell iostat to omit output for any devices for which there was no activity during the sample period.

Environment

The iostat command takes into account the following environment variables:

S_TIME_FORMAT	If this variable exists and its value is ISO then the current locale will be ignored when printing the date in the report header. The iostat command will use the ISO 8601 format (YYYY-MM-DD) instead. The timestamp displayed with option -t will be also be compliant with ISO 8601 format.
POSIXLY_CORRECT	When this variable is set, transfer rates are displayed in 512-K blocks instead of the default 1K blocks.

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iostat 例子

iostat

顯示所有CPU和設備的單個“自啟動以來的歷史記錄”報告。

iostat -d 2

每兩秒顯示一次連續的設備報告。

iostat -d 2 6

對于所有設備，每兩秒鐘顯示六個報告。

iostat -x sda sdb 2 6

對于設備sda和sdb，以兩秒鐘的間隔顯示六個擴展報告。

iostat -p sda 2 6

顯示在用于設備兩秒的時間間隔的六個報告SDA和設備的所有分區SDA（SDA1，SDA2，等等）。

iostat

Display a single history-since-boot report for all CPU and Devices.

iostat -d 2

Display a continuous device report at two-second intervals.

iostat -d 2 6

Display, for all devices, six reports at two-second intervals.

iostat -x sda sdb 2 6

Display, for devices sda and sdb, six extended reports at two-second intervals.

iostat -p sda 2 6

Display six reports at two-second intervals for device sda and all the partitions of device sda (sda1, sda2, etc.).

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其他命令行

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