Why would my server be swapping...

Wouter van Vliet wouter.van.vliet at gmail.com
Thu Oct 14 15:02:16 UTC 2004


On Thu, 14 Oct 2004 09:45:37 -0500, Tommy Reynolds
<tommy.reynolds at megacoder.com> wrote:
> Uttered Wouter van Vliet <wouter.van.vliet at gmail.com>, spake thus:
> 
> >Crappy intro, huh? Anyway, I've got a question - bit of an oddity I
> >noticed in the output to the "free" command. I'll post that output
> >before I continue:
> >
> >             total       used       free     shared    buffers     cached
> >Mem:        515536     196040     319496          0      22448     120144
> >-/+ buffers/cache:      53448     462088
> >Swap:      1052248     151476     900772
> >
> >Hope the mail brings it over nice and columny. Anyway, what it shows
> >is 311 megabytes of free memory and 147MB used swap space. Isn't that
> >a bit odd, and shouldn't the server only be swapping when all (or at
> >least most) of the RAM is in use?
> 
> Nope, not odd at all.  The kernel does "anticipatory swapping" by
> moving VM pages out that haven't been used in a while: this is called
> "buffer aging".  This is a "good thing" because it helps the kernel
> have more free memory ready for a burst of activity in the future.
> 
> No worries, mate.

but, .. but, ... I was told that swapping is bad, bad evil even
always. If I'd ask you'd probably tell me Santa doesn't exist either?
:P

Thanks for the info!

I'd still like to know what's using that much memory and why the usage
is only increasing, why almos nothing is running - currently just a
webserver serving an "unavailable" html page, since we've had some
problems in the past week with incredibly high loads. Woke up 
wednesdaymorning at 6am after the server dinied all service the night
before and still saw a load of 70 on the 15min avg. Anyway, drifting
off. Besides the apache server there's postgres, doing nothing. And
MySQL, doing nothing. And that's basically everything.




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