Linux iostat command learning notes

Linux iostat command learning notes
1. Command Introduction

Iostat (I/O statistics input/output statistics) command to monitor system disk operation activities. It reports disk activity statistics and CPU usage.

2. Usage

Iostat [Option] [<time interval> [<times>]

3. Option-c: Only displays CPU usage;

-D: only display the device utilization. It is generally not used with-c.

-K: The display status is measured in kilobytes per second instead of blocks per second;

-M: The display status is measured in megabytes per second;

-N: Display disk array (LVM) Information

-N: displays NFS usage

-P: Only displays the status of the block device and all other partitions used;

-T: displays the time when each report is generated;

-V: displays the version number and exits;

-X: displays the scaling status.

4. Example 1: iostat command description

Detailed Description: the second line is system information and monitoring time,

Lines 3 and 4 show CPU usage

% User	Percentage of time when the CPU is in user mode.
% Nice	Percentage of time when the CPU is in user mode with NICE value.
% System	Percentage of time when the CPU is in system mode.
% Iowait	Percentage of CPU waiting for input/output completion time.
% Steal	The percentage of idle waiting time of the virtual CPU when the hypervisor maintains another virtual processor.
% Idle	Percentage of idle CPU time.

I/O output information

Device	Block device name
Tps	The number of I/O transfers per second. Multiple I/O requests can be combined into one, and the number of bytes transmitted by each I/O request is different. Therefore, multiple I/O requests can be combined into one.
Blk_read/s	Number of read parts per second
Blk_wrtn/s	Number of read parts per second
Blk_read	Indicates the total number of data block reads since the system is started.
Blk_wrtn	Indicates the total number of data block writes since the system is started.

Example 2: Use the-x parameter to obtain more statistics.

[Root @ Oracledb ~] # Iostat-x
Linux 2.6.32-573.8.1.el6.x86 _ 64 (oracledb) February _ x86_64 _ (4 CPU)

Avg-cpu: % user % nice % system % iowait % steal % idle
0.06 0.00 0.12 0.05 0.00 99.76

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm % util
Sda 2.62 0.84 2.91 0.38 202.32 9.75 64.61 0.00 1.44 0.76 0.25

Example 3: view the cpu status

[Root @ oracledb ~] # Iostat-c Linux 2.6.32-573.8.1.el6.x86 _ 64 (oracledb) August 29 _ x86_64 _ (4 CPU) avg-cpu: % user % nice % system % iowait % steal % idle 0.06 0.00 0.12 0.04 0.00

Example 4: view the disk read/write speed, in k

[Root @ oracledb ~] # Iostat-d-k Linux 2.6.32-573.8.1.el6.x86 _ 64 (oracledb) August 29 _ x86_64 _ (4 CPU) Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtnsda 3.20 98.34 4.77 933682 45257

Example 5: iostat-d 2 3 indicates that there is no 2-second check, and a total of 3 checks

[Root @ oracledb ~] # Iostat-d-k 2 3 Linux 2.6.32-573.8.1.el6.x86 _ 64 (oracledb) August _ x86_64 _ (4 CPU) Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtnsda 3.16 97.25 4.72 933682 45289 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtnsda 0.00 0.00 0.00 0 0 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtnsda 0.00 0.00 0.00 0 0

Example 6: view the status of a block device or partition

[Root @ oracledb ~] # Iostat-m-p/dev/sdaLinux 2.6.32-573.8.1.el6.x86 _ 64 (oracledb) February 28 _ x86_64 _ (4 CPU) avg-cpu: % user % nice % system % iowait % steal % idle 0.06 0.00 0.12 0.04 Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtnsda 3.07 0.09 0.00 911 44sda1 0.07 0.00 0.00 2 0sda2 0.03 0.00 0.00 1 0sda3 2.95 0.09 0.00 44

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