Example of "iostat" output

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
sda               0.00     3.00    0.00    4.00     0.00    28.00    14.00     0.01    2.50   2.50   1.00
scd0              0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00   0.00   0.00

explanations for some fields:
• wrqm/s - the number of write requests merged per second.
• w/s - the number of write requests that were sent to the device, per second.
• wKB/s - number of KB of data written to the device in the last second.
• avgrq-sz - average size (in sectors - typically 512 bytes long) of request that was sent to the device.
• avgqu-sz - average size of the queue of requests waiting to be sent to the device.
• await - average time (milli-seconds) to handle a request (includes time waiting in block-layer queue plus svctm)
• svctm - average time (milli-seconds) it took the disk to service a request (not including time waiting in the block-layer queue)

Originally written by guy keren