Iostat

iostat(input/output statistics) is a computer system monitor tool used to collect and show operating system storage input and output statistics.

Usage:

• iostat
• iostat -x, includes among other information %util column. sar -d also display %util information.
• iostat -xc

-c     Display the CPU utilization report

Example: iostat -x

Linux 4.15.0-66-generic (server_name_1) 	01/06/2019 	_x86_64_	(12 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          26.69    0.09    5.45    2.81    0.00   64.95

Device            r/s     w/s     rkB/s     wkB/s   rrqm/s   wrqm/s  %rrqm  %wrqm r_await w_await aqu-sz rareq-sz wareq-sz  svctm  %util
loop0            0.00    0.00      0.00      0.00     0.00     0.00   0.00   0.00    0.03    0.00   0.00     2.49     0.00   0.00   0.00
loop1            0.00    0.00      0.00      0.00     0.00     0.00   0.00   0.00    0.11    0.00   0.00    10.11     0.00   0.00   0.00
loop2            0.08    0.00      0.08      0.00     0.00     0.00   0.00   0.00    0.46    0.00   0.00     1.07     0.00   0.01   0.00
loop3            0.07    0.00      0.07      0.00     0.00     0.00   0.00   0.00    0.23    0.00   0.00     1.03     0.00   0.01   0.00
loop4            0.00    0.00      0.00      0.00     0.00     0.00   0.00   0.00    0.00    0.00   0.00     2.50     0.00   0.00   0.00
sda              9.24   13.63     61.04    338.74     2.22     5.29  19.36  27.97    0.22    0.37   0.01     6.61    24.85   0.09   0.20
sdb             62.13  185.19  10293.49   7751.52     0.93     0.95   1.47   0.51    1.70   17.34   3.32   165.69    41.86   0.42  10.46
sdc             46.22  203.85   9157.51  10073.27     0.91     0.57   1.94   0.28    1.59   17.32   3.60   198.14    49.42   0.44  11.11
sdd             59.95    9.98  10592.98   9774.97     0.20     3.44   0.34  25.63    1.62  173.61   1.83   176.71   979.46   1.75  12.21
dm-0           110.19  301.03  19451.00  28437.01     0.00     0.00   0.00   0.00    1.88    7.24   2.39   176.52    94.47   0.44  18.29

%rrqm The percentage of read requests merged together before being sent to the device.

Related commands

• nfsiostat
• Device mapper

See also

• hdparm
• nice and ionice
• Performance: IO performance: iotop, iostat, sar -d, fio, nmon, vmstat -d, dd, nmon, stress
• Performance: sysstat, sar, sadc, debian-sa1, sa1, sa2, iostat, nfsiostat mpstat, changelog, /usr/lib/sysstat/sadc, /etc/sysstat/sysstat, pidstat, irqstat