When you've got a single-function box, and you know you can tune it to stop
short of swap, I think it's probably fine to go without swap.  For
simplicity and consistency, we have swap turned on for our webservers, but
honestly, if they ever started swapping (and we make sure they have enough
memory and are tuned that they really can't), they'd be so slow as to be
useless for their function.  We turn swappiness (linux) to 0 and do
everything we can to prevent swapping - and we monitor it, so if they ever
swap, we get paged.  (They don't.)
When you're talking about high performance and low latency, in my opinion,
swap is bad.  But having it just so the box doesn't crash and burn when
something does eat a lot of memory is probably ok.

Nicholas



On Fri, Sep 11, 2009 at 1:18 PM, Shane Milburn <[email protected]> wrote:

> I'm doing a project for a $CLIENT who has requested that I build out a
> small web farm capable of serving 1M hits an hour average and peak traffic
> to 3M/hour. No problem there but when building the systems we got into a
> debate about how he wants the OS built. Basically he said DO NOT build a
> swap partition or swap file. I asked why and his response was "These are
> cookie cutter web servers that do nothing other than serve apache requests.
> They have nothing else on them so we'll run apache up to XXX for MaxClients
> and MaxSpareServers (just shy of running the box out of memory) and leave
> it. "
> He's the $CLIENT and I'l build it the way he requests but my questions
> are...
>
>
>    1. Would/Have you run a web server without swap? (they have 500Gb
>    drives in them so there's room for a swap partition.)
>    2. Any benefits or drawbacks to doing this?   (in context of a pure
>    webserver that does nothing else but serve pages as part of the pool it is 
> a
>    member of.)
>
>
> Happy Friday!
>
>
> cheers,
> -shane
> --
>
>
>
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