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vmstat: negative values?!

vmstat: negative values?!

Hello, i'm monitoring a largely stressed system. That's an rp5470 (L3000-5xx) w/ 2 550MHz CPU 4 GB of mem running a J2EE app and an Oracle 9i database.

What is confusing me now is the negative values in the response to the "vmstat -f" command :

# vmstat -f
3031208 forks, -433171143 pages, average= -142.90

Any hints?
Thx in advance
Respected Contributor Respected Contributor

Re: vmstat: negative values?!

The values in vmstat are signed data types so they can overflow as the counter gets larger. This should appear if your system is up for a very long time or the memory page swapping is too high.

Honored Contributor Honored Contributor

Re: vmstat: negative values?!

It says, ..."vmstat tries to present an average since boot on the first line. The
first line of vmstat output is utter garbage and must be discarded"

I was only running vmstat for a single count. When run with mutiple counts
the stats after the first line are reported accurately. ""

"A ship in the harbor is safe, but that is not what ships are built for"
Respected Contributor Respected Contributor

Re: vmstat: negative values?!

Hi Alberto,

It is overflow.
Try first to clear with

vmstat -z


Re: vmstat: negative values?!

Thank you for all the replies. In fact i suspected of some kind of overflow but now i have the confirmation.