Friday, August 19, 2011

Understanding vmstat output

As we know vmstat is very useful command to monitor system performance in linux. I issued this command on my RHEL Server, and output is as follows

root# vmstat

procs -------- --------memory------ ---swap--- --io-- ----system- ---cpu--------

r b swpd free buff cache si so bi bo in cs us sy id wa st

0 0 128 1217472 302800 2383476 0 0 17 14 10 15 0 0 100 0 0

What we can conclude from this output ?

Let us first understand, meaning of this result.

procs refer process. r for running and b for blocking.

swpd refer swapping free refer free memory, buff memory used in buffering and so for cache

swap section include swap in(si) and swap out (so)

io section include block in (bi) and block out(bo)

system section include interrupt(in) and context switch (cs)

cpu in important section, it include cpu usage by us(user) and sy(system) process,id (idle) percentage of cpu. wa refer time waiting for IO and st refer time stolen from virtual machine.