Multiple varnish instances per server?
Michael S. Fischer
michael at dynamine.net
Sun Jun 1 19:38:24 CEST 2008
Why are you using Varnish to serve primarily images? Modern webservers
serve static files very efficiently off the filesystem.
On Sun, Jun 1, 2008 at 8:58 AM, Barry Abrahamson <barry at automattic.com>
> Is anyone running multiple varnish instances per server (one per disk
> or similar?)
> We are currently running a single varnish instance per server using
> the file backend. Machines are Dual Opteron 2218, 4GB RAM, and 2
> 250GB SATA drives. We have the cache file on a software RAID 0
> array. Our cache size is set to 300GB, but once we get to 100GB or
> so, IO starts to get very spiky, causing loads to spike into the 100
> range. Our expires are rather long (1-2 weeks). My initial thoughts
> were that this was caused by cache file fragmentation, but we are
> seeing similar issues when using the malloc backend. We were thinking
> that running 2 instances per server with smaller cache files (one per
> physical disk), may improve our IO problems. Is there any performance
> benefit/detriment to running multiple varnish instances per server?
> Is there a performance hit for having a large cache?
> Request rates aren't that high (50-150/sec), but the cached files are
> all images, some of which can be rather big (3MB).
> Also, is anyone else seeing similar issues under similar workloads?
> Barry Abrahamson | Systems Wrangler | Automattic
> Blog: http://barry.wordpress.com
> varnish-misc mailing list
> varnish-misc at projects.linpro.no
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