Apr 2017

IOStat gives information (disk performance) about the disk activity in a Linux environment. Useful information such as disk reads/writes and activity (% busy).

IOStat is a handy tool to ensure that you are not overworking the disks, this is especially useful on products like VSPP where disk usage can be exceeded before any CPU performance issues occur.

To use, from the command line simply enter iostat
<sxh [text][; options for SyntaxHighlighter]> iostat

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

        33.60    0.00    0.50    0.02    0.00   65.87

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 7.36 0.19 1112.01 967702 5556997874 sdb 0.00 0.00 0.00 1496 0 dm-0 139.00 0.19 1112.01 956514 5556997832 dm-1 0.00 0.00 0.00 2400 0 dm-2 0.00 0.00 0.00 2178 24 </sxh>
We can use another command line to get periodica.iostat updates iostat 10 -x

iostat 10 -x


avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          33.61    0.00    0.50    0.02    0.00   65.86

Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
sda               0.00   132.62    0.00    7.36     0.19  1112.07   151.05     0.05    6.75    2.34    6.75   3.01   2.22
sdb               0.00     0.00    0.00    0.00     0.00     0.00     8.00     0.00    0.18    0.18    0.00   0.18   0.00
dm-0              0.00     0.00    0.00  139.01     0.19  1112.07     8.00     0.71    5.13    3.92    5.13   0.16   2.22
dm-1              0.00     0.00    0.00    0.00     0.00     0.00     8.00     0.00    1.42    1.42    0.00   0.60   0.00
dm-2              0.00     0.00    0.00    0.00     0.00     0.00     7.92     0.00    0.59    0.51    5.00   0.44   0.00