Can you publish your testing methods and configurations for both Varnish and Nginx? Can you include the Network graphs and/or the Connections graphs for Varnish and Nginx?
-Travis On 8/16/13 12:29 PM, "Bryan Stillwell" <[email protected]> wrote: >I'm looking at converting all of our nginx caching servers over to >varnish, but I'm seeing some oddities with the 'file' storage backend >that I'm hoping someone could shed some light on. > >Hardware specs for both machines: > >Dell PowerEdge R610 > Dual Xeon E5620 @ 2.40GHz > 64GiB memory > 4x 240GB SSDs in a RAID5 attached to a PERC H700 RAID controller > >The following image compares CPU, memory, and IOPS for both a machine >running varnish (left), and one running nginx (right): > >http://i1217.photobucket.com/albums/dd391/bstillwell_pb/Graphs/varnish-vs- >nginx.png > >At the most recent sample, each machine was handling ~350 requests/sec. > >As you can see the varnish machine has a lot more CPU time dedicated to >I/O wait, which matches up with ~5x higher IOPS numbers. However, the >biggest difference is that varnish is using ~25x more read IOPS than >nginx. > >As for the jumps in the IOPS graph, I believe they can be explained by: > >Wednesday @ 10:00a: Started taking traffic >Wednesday @ 11:00a: Memory cache filled, started using SSDs >Wednesday @ 4:00p: TTL of 6 hours was hit, objects start expiring >Wednesday @ 7:15p: SSD cache filled > >I pre-allocated the storage with fallocate (fallocate -l 450g >/cache/varnish_storage.bin) to make sure that wasn't helping contribute >to the issue. > >Any ideas on what could be tuned to reduce the number of read IOPS to be >more inline with nginx? > >Thanks, >Bryan > >_______________________________________________ >varnish-misc mailing list >[email protected] >https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc > _______________________________________________ varnish-misc mailing list [email protected] https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
