= Linux/DiskSpeedPerformance =

 * How to check and analize disk to find slow disk issues

== iostat ==
 * [[https://www.techrepublic.com/article/how-to-use-the-linux-iostat-command-to-check-on-your-storage-subsystem/|iostat labels]]
   * %util – Percentage of elapsed time during which I/O requests were issued to the device.
   * r_await, w_await – The average time (in milliseconds) for read / write requests issued to the device to be served.


 * install {{{
apt install sysstat
}}}
 * run iostat {{{
iostat -x 1 3
}}}
   * the numbers after the -x(extended) is 1 - delay, and 3 -repeat

== ps aux ==
 * browse processes waiting for I/O, use watch to monitor processes with STAT flag 'D' like below: {{{
watch -n 1 "(ps aux | awk '\$8 ~ /D/  { print \$0 }')"
}}}


== Basic disk operations ==
 * See mounted disk e.g. sda {{{
mount | grep "/dev/sd"
}}}
 * scsi details - e.g. to map how they are mounted from cloud provider {{{
$ sudo lsscsi
}}}

== Azure ==
 * find disks {{{
az vm show -g myResourceGroup -n myVM --query "storageProfile.dataDisks"
}}}

]

----
CategoryPerformance