Disk usage and disk utilization are different on Linux. Disk usage means how much percent of space we use on the disk. Disk utilization means how busy the disk is when there is some workload on it. Today we will look at more details about this.
How to check disk usage on Linux?
df command can be used to show disk usage. We can get how much percent space we already used on this disk or disk partition from Use% column. If it is over 80%, we should check which file or directories take up this space. Then we can remove some unwanted files to release the space.
# df -h Filesystem Size Used Avail Use% Mounted on devtmpfs 16G 0 16G 0% /dev tmpfs 16G 1.7G 14G 11% /dev/shm tmpfs 16G 834M 15G 6% /run tmpfs 16G 0 16G 0% /sys/fs/cgroup /dev/mapper/wbx_vg-root 20G 1.8G 18G 9% / /dev/mapper/wbx_vg-opt 9.8G 217M 9.6G 3% /opt /dev/mapper/wbx_vg-tmp 4.9G 45M 4.9G 1% /tmp /dev/mapper/wbx_vg-u00 43G 20G 24G 46% /u00 /dev/mapper/wbx_vg-var 9.8G 757M 9.1G 8% /var /dev/mapper/wbx_vg-var_crash 33G 39M 33G 1% /var/crash /dev/sdo1 509M 159M 350M 32% /boot
How to check disk utilization on Linux?
Iostat command can be used to show disk utilization. We can get how busy our disk is when there is some workload on it from column %util. If it is over 80%, we need check the workload like iops, io size or storage latency to fix it. More details here about disk utilization.
# iostat -kx 3 /dev/sdo Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sdo 0.06 0.78 1.62 13.27 98.69 177.04 37.04 0.50 33.48 72.83 28.68 4.21 6.27 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sdo 0.00 0.00 0.00 12.00 0.00 82.50 13.75 0.18 15.22 0.00 15.22 4.56 5.47