varnish constant hdd write

Per Buer perbu at
Wed Jun 9 10:18:50 CEST 2010

You're right. Varnish would only have 1GB of memory to store objects.
Linux doesn't really do paging very well so your wise to stay within
the boundaries of physical memory.

This might not be so bad if your backend if somewhat snappy. If your
web site is news or portal like most of the 'hot' content will be the
content linked from the front page + related content. In most cases a
web site won't have more than 100MB of 'hot' content and such 1GB of
cache will go a really long way.


On Wed, Jun 9, 2010 at 9:53 AM, Alex F <alex at> wrote:
> SSD would be a good choice indeed. But not possible right now.
> I searched about malloc and see that it is used mostly when one has much
> available RAM. My current system only has 4GB and there is no hope on
> upgrading.
> My highest peak on cached objects was 126.000 (with 1 day TTL) and highest
> Virtual Mem allocated 2.1GB.
> Available RAM right now is at 1.6GB, but I'd say 1GB given the fact that
> apache+resin+lighttpd also reside on this machine.
> Now if I configure Varnish to use malloc 1GB, it only has 1GB to store
> objects, right?
> On 8.6.2010 17:15, Per Buer wrote:
>> Hi.
>> There have been changes in both the FreeBSD and Linux vm in recent
>> years and the file backend doesn't perform as good on rotating hard
>> drives as it used to. Modern virtual machines seem to be much more
>> aggressive when writing.
>> I would recommend you try using malloc or getting a SSD. Or try going
>> back to RHEL4 or FreeBSD 6. :-)
>> Per.

Per Buer,  Varnish Software
Phone: +47 21 54 41 21 / Mobile: +47 958 39 117 / skype: per.buer

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