Difference between Sar and Vmstat

blurblur · 04-28-2005, 10:35 PM

Hello,

I have a question regarding vmstat and sar -B. When I run vmstat , it shows value of zero for si and so parameter (under swap). But when I run sar -B, the pgpgin/s and pgpgout/s are showing values.

Si and So measure the memory being page in and page out , right? Kind of confuse here. Arent' they suppose to match the pgpgin/s and pgpgout/s shown in sar?

Please advise.
Thanks alot.
BlurBlur

Tinkster · 05-02-2005, 03:26 PM

I suppose it depends on how sar is run in general ...

If you just run "sar -B" as such it will get the information
from the most recently written to file, while vmstat will give
you in-situ stats ...

Cheers,
Tink

blurblur · 05-03-2005, 08:54 PM

Hello Tink,

Thanks! But can you elaborate more as to what you mean by "most recently written to file" and "in-situ stats"?

How can I run sar such that it will show the same information as vmstat then?

Cheers,
Blur

Tinkster · 05-03-2005, 09:14 PM

sar -B 1

Read the manpage ;}

"In situ" means "right now".

Cheers,
Tink