Ardika Sulistija: Created page with " iostat - Report Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions. $ iostat Linux 4.14.158-129.185.amzn2.x86_64 (ip-172-31-33-239.ec2.internal) 02/24/2020 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.15 0.00 0.11 0.01 0.04 99.70 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn nvme0n1 0.86 2.81 5.86..."

2024-08-27T00:28:37Z

Created page with " iostat - Report Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions. $ iostat Linux 4.14.158-129.185.amzn2.x86_64 (ip-172-31-33-239.ec2.internal) 02/24/2020 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.15 0.00 0.11 0.01 0.04 99.70 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn nvme0n1 0.86 2.81 5.86..."

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iostat - Report Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions.

$ iostat
Linux 4.14.158-129.185.amzn2.x86_64 (ip-172-31-33-239.ec2.internal) 02/24/2020 _x86_64_ (2 CPU)

avg-cpu: %user %nice %system %iowait %steal %idle
0.15 0.00 0.11 0.01 0.04 99.70

Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
nvme0n1 0.86 2.81 5.86 3308340 6902350

$ iostat -xm
Linux 4.14.193-149.317.amzn2.x86_64 (ip-172-31-35-82.ec2.internal) 03/04/21 _x86_64_ (2 CPU)

avg-cpu: %user %nice %system %iowait %steal %idle
0.22 0.00 0.09 0.01 0.06 99.63

Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
nvme0n1 0.00 0.03 0.01 0.99 0.00 0.01 20.23 0.00 0.65 0.78 0.65 0.12 0.01

* Tps : lists the transfers per second to the device. “Transfers” is another way to say I/O requests sent to the device.
* Blk_read/s : The number of blocks read from the device per second.
* Blk_wrtn/s : The number of blocks written to the device per second.
* Blk_read : The total number of blocks read from the device.
* Blk_wrtn : The total number of blocks written to the device.

You can use iostat to determine which drive partition is currently under heavy I/O load.

Once you have determined the drive partition that is under heavy I/O load, next is to identify whether the I/O is mostly from reads or writes.
* Side note: you may have to run iostat more than one time to get an accurate sense of the current I/O on your system.
** $ iostat n ; will print output every ‘n’ seconds. For example:
# Prints every 2 seconds
$ iostat 2
Linux 4.14.158-129.185.amzn2.x86_64 (ip-172-31-33-239.ec2.internal) 02/24/2020 _x86_64_ (2 CPU)

avg-cpu: %user %nice %system %iowait %steal %idle
0.15 0.00 0.11 0.01 0.04 99.70

Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
nvme0n1 0.86 2.81 5.87 3312908 6925355

avg-cpu: %user %nice %system %iowait %steal %idle
0.25 0.00 0.25 0.00 0.00 99.50

Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
nvme0n1 0.00 0.00 0.00 0 0

avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.00 0.00 0.00 100.00

Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
nvme0n1 0.00 0.00 0.00 0 0

iostat – try it with the -xm 2 options for extended statistics, in megabytes, and in two-second intervals.

From Samyak (useful to run while running fio benchmark tests!!!) - captures iostat every 1 sec for 10 mins:
iostat -xdmzt 1 600

‘iotop’ - a mix between ‘top’ and ‘iostat’ that shows you all of the running processes on the system sorted by their I/O statistics.

Read more: https://coderwall.com/p/utc42q/understanding-iostat

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