vmstat (virtual memory statistics) is a computer system monitoring tool that collects and displays summary information about operating system memory, processes, interrupts, paging and block I/O. Users of vmstat can specify a sampling interval which permits observing system activity in near-real time.
The vmstat tool is available on most Unix and Unix-like operating systems, such as FreeBSD, Linux or Solaris. The syntax and output of vmstat often differs slightly between different operating systems.
VMstat Example:
#> vmstat 2 6 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 2536 21496 185684 1353000 0 0 0 14 1 2 0 0 100 0 0 0 2536 21496 185684 1353000 0 0 0 28 1030 145 0 0 100 0 0 0 2536 21496 185684 1353000 0 0 0 0 1026 132 0 0 100 0 0 0 2536 21520 185684 1353000 0 0 0 0 1033 186 1 0 99 0 0 0 2536 21520 185684 1353000 0 0 0 0 1024 141 0 0 100 0 0 0 2536 21584 185684 1353000 0 0 0 0 1025 131 0 0 100 0 #>In the above example the tool reports every two seconds for six iterations.
We can get the customized or required outputs by using various options with vmstat command.
Example:
#vmstat –s this option is use to get Memory Statistics.
#vmstat –d this option is use to get Disk Statistics.