Iostat

iostat is a command-line utility that reports CPU statistics and input/output statistics for devices and partitions.

iostat command

#The basic syntax of the iostat command
$iostat [options] [interval [count]]

#options: options can be used to specify the type of statistics to be displayed, such as disk statistics, CPU utilization statistics, etc.
#interval: The interval parameter specifies the amount of time in seconds between each report
#count:The count parameter can be specified in conjunction with the interval parameter. If the count parameter is specified, the value of count determines the number of reports generated at interval seconds apart. If the interval parameter is specified without the count parameter, the iostat command generates reports continuously.

iostat output

#iostat output example
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util
device 0.00 0.00 100 50 50 100 10 3.00 0.00 0.00 5.00

# IOPS from the output
The IOPS for this device is r/s + w/s = 100 + 50 =150

iostat output label and meaning

column	Description
rrqm/s	the number of read requests that were merged per second
wrqm/s	the number of write requests that were merged per second
r/s	the number of reads per second
w/s	the number of writes per second
rkB/s	the number of kilobytes read per second
wkB/s	the number of kilobytes written per second
avgrq-sz	the average size of each request in sectors
avgqu-sz	the average queue length of the requests
await	the average time (in milliseconds) that each request spent in the queue
svctm	the average service time (in milliseconds) for each request
%util	the percentage of time that the disk was active