Strategy for large cache sets
ottolski at web.de
Thu Jul 3 18:25:30 CEST 2008
Am Dienstag 01 Juli 2008 20:16:15 schrieb Skye Poier Nott:
> I want to deploy Varnish with very large cache sizes (200GB or more)
> for large, long lived file sets. Is it more efficient to use large
> swap or large mmap in this scenario?
> According to the FreeBSD lists, even 20GB of swap requires 200MB of
> kern.maxswzone just to keep track of it, so it doesn't seem like that
> will scale too well. Is one or the other method better for many
> small files vs less many big files?
> Thanks again... when I'm a Varnish expert I'll help the newbs :)
I'm administrating three varnish instances for static images; cache file
is setup as 517 GB (pre allocated with "dd"); currently, after 35 days
uptime, it's filled more than half:
305543155712 bytes allocated
248759787520 bytes free
It's running on Debian etch, 2x dual-core amd opteron, 32 GB RAM, 30 GB
Mem: 32969244k total, 32870944k used, 98300k free, 120672k buffers
Swap: 29045480k total, 6096612k used, 22948868k free, 25752752k cached
the varnish process looks like this in "top":
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ P COMMAND
3221 username 15 0 522g 27g 21g S 1 87.0 539:33.89 2 varnishd
hitrate is 98% for recent short term, overall average is 95%.
load of the machines is between 1 and 2 on medium traffic times, and
goes up to 3 only seldom.
but, the request rate is may be relatively low, compared to what others
reported on the list. I don't have hard numbers unfortunately, average
is 80.49 according to varnishstat. At peaks the reate may be in the
order of may be 400 req/sec for a single instance.
We had issues with 1.1.2 crashing, but since running on trunk (r2640),
everything runs smooth. response time according to a nagios http
response check is between 0.5 - 1 seconds, almost never over 1 second,
even at peak times.
Hope it's useful for someone, let me know if you need more details.
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