5 Linux commands for measuring disk activity

$ dstat -d 10
-dsk/total-
read  writ
949B   73k
65k   81M  

Notice that the reported data may be shown in a number of different units — e.g., M (megabytes), k (kilobytes), and B (bytes).

The dstat command provides valuable insights into overall Linux system performance, pretty much replacing a collection of older tools, such as vmstat, netstat, iostat, and ifstat, with a flexible and powerful command that combines their features. For more insight into the other information that the dstat command can provide, refer to this post on the dstat command.

2. iostat

The iostat command helps monitor system input/output device loading by observing the time the devices are active in relation to their average transfer rates. It’s sometimes used to evaluate the balance of activity between disks.

$ iostat
Linux 6.8.9-100.fc38.x86_64 (fedora)    11/05/2024      _x86_64_        (2 CPU)
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
2.42    0.19    1.44    0.44    0.00   95.52
Device    tps  kB_read/s  kB_wrtn/s  kB_dscd/s  kB_read  kB_wrtn  kB_dscd
loop0    0.11       0.24       0.00       0.00      771        0        0
loop1    0.01       0.02       0.00       0.00       63        0        0
sda     25.13     685.20     175.07     102.58  2194224   560621   328480
zram0    3.98       0.94      15.27       0.00     3000    48900        0

Of course, all the stats provided on Linux loop devices can clutter the display when you want to focus solely on your disks. The command, however, does provide the -p option, which allows you to just look at your disks — as shown in the commands below.

$ iostat -p sda
Linux 6.8.9-100.fc38.x86_64 (fedora)    11/05/2024      _x86_64_        (2 CPU)
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
2.21    0.17    1.35    0.41    0.00   95.86
Device     tps  kB_read/s  kB_wrtn/s  kB_dscd/s  kB_read  kB_wrtn  kB_dscd
sda      27.40     618.74     162.08    1297.02  2194423   574849  4600040
sda1      0.05       1.70       0.00     167.39     6022        1   593676
sda2      0.05       1.26       0.04     192.96     4469      152   684352
sda3     27.27     615.38     162.04     936.67  2182528   574696  3322012

Note that tps refers to transfers per second.

You can also get iostat to provide repeated reports. In the example below, we’re getting measurements every five seconds by using the -d option.