On Thu, Sep 15, 2011 at 11:29, Aurélien Lemaire <[email protected]>wrote:
> ** > Good day folks, > > First of all, varnish is an outstanding piece of software that my company > and i are addicted to. So thanks to all the coders. > > Here is my problem : > I allocated varnish 1G of RAM on a website that can have more than 2 Go of > possible cacheable objects . Not to worry though as any proxy-cache system > should smartly nuke old objects to make place to new one to live peacefully > within its allocated RAM. And that's where Varnish behave unexpectedly : > each time it need to nuke SOME objects : it nukes ALMOST ALL of them (often > ~80% of my 35k objects) which is quite aggressive ; thus i lost almost all > my cache....IRK ! > > 3 Munin graphs attached to see the problem clearly : big drop each time a > nuking happens. > > To make sure my pbr is about varnish nuking system : i increased from 1G to > 3G(more than the max possible 2G cacheable objects) on another varnish of > this platefom (this website is delivered by multiple front/varnish server > all stricly similar and independant) and this issue disappeared (no more > nuking : no lost of ~80%of my objects) > > Here is my env : > Debian 5.0.8 64 bits on 2.6.32-5-openvz-amd64 kernel > Varnish 2.1.3 SVN 5049:5055(debian package 2.1.3-8) > 200 varnish 's worker threads running constantly (no issue on workers) > 30req/s average with 60/s in peak > > Daemon run as such : > /usr/sbin/varnishd -P /var/run/varnishd.pid -a :80 -T localhost:6082 -S > /etc/varnish/secret -f /etc/varnish/serverx.vcl -w 100,1024 -s > file,/var/lib/varnish/serverx/varnish_storage.bin,3G > > Here a quick varnishstat -1 : > > Is it normal varnish behaviour ? sounds like a bug to me. > Am i missing some tuning (lru_interval) to soften the nuking algo ? > Do you need more info ? > helps appreciated here ;-) > > Regards, Aurelien Lemaire > > It could be someone downloading a large file (like a ~700Mb iso file) and varnish nuking objects to make room for this file (even if its configured to not cache it). Try to get a varnishlog trace of the moment the nuking begins. -- Jorge Nerín <[email protected]>
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