does varnish write objects to disk?

Nagita Karunaratne nagita.k at
Mon Jan 15 19:55:42 CET 2007

Thanks for your help. I take it you let the kernel manage as much as possible.

But I really want to know how I can improve performance in a
multi-cpu, multi-core processor systems running multiple cms-websites
in a virtual hosting configuration outside the scope of the kernel.

For example, a specific RAID configuration that will make it easier
for varnish. Or do I leave it all up to the kernel.

Is FreeBSD and Linux2.6 equally capable with respect to varnish?


On 1/15/07, Poul-Henning Kamp <phk at> wrote:
> In message <45ABC845.8010202 at>, Flemming Frandsen writes:
> >Poul-Henning Kamp wrote:
> >>>Varnish caches objects into *memory* and not disk right?
> >>
> >> No, varnish caches objects into "virtual memory" which means that
> >> RAM acts as a cache for the disk.
> >
> >I guess the interesting detail is how eager the kernel is to write the
> >mapped memory to disk.
> >
> >It would be a shame to spend time and IO bandwidth to write a 1G cache
> >out to disk if the box has 4G of RAM and would never need the RAM for
> >anything other than the cache, woudn't it?
> The kernels I know of can be described as distinctively reluctant
> to write things out.
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
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