vmstat

vmstat 1

* High values in “wa” column mean: IO problem
* High values in “si”, “so” mean: excessive swapping

Sustained high swap rates (si and so) are usually bad. The system will start spending all of its time swapping, and make no progress on any actual work. You will also see the number of runnable (r and b) processes increase. If the situation gets bad enough and free memory gets too low, the Out-of-memory (oom) logic will start killing random processes. At this point, either reducing the number of processes that normally run or adding additional RAM are about the only options.

vmstat – Report virtual memory statistics

vmstat reports information about processes, memory, paging, block IO, traps, and cpu activity.

The first report produced gives averages since the last reboot. Additional reports give information on a sampling period of length delay. The process and memory reports are instantaneous in either case.

FIELD DESCRIPTION FOR VM MODE

FIELD DESCRIPTION FOR DISK MODE

FIELD DESCRIPTION FOR DISK PARTITION MODE

FIELD DESCRIPTION FOR SLAB MODE

Related commands

* iostat
* sar
* mpstat
* ps
* top
* free

See Linux Commands

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