On Fri, May 6, 2011 at 4:21 PM, Shane Hathaway <sh...@hathawaymix.org> wrote: > On 05/06/2011 02:14 PM, Jim Fulton wrote: >>> >>> It sounds like you primarily need a bigger and faster cache. If you >>> want to make minimal changes to your setup, try increasing the size of >>> your ZEO cache and store the ZEO cache on either a RAM disk (try mount >>> -t tmpfs none /some/path) or a solid state disk. Remember that seek >>> time is 5-10 ms with spinning drives, so putting a ZEO cache on a >>> spinning drive can actually kill performance. >> >> If this on Linux and you have enough RAM, the data should be in the >> disk cache anyway, so I don't see any benefit to a RAM disk. > > If there is memory pressure then Linux will evict some of the cache from > RAM, causing the ZEO cache to be much slower than the ZEO server. I've seen > that happen often.
If there is memory pressure and you take away ram for a ram disk, then you're going to start swapping, which will give you other problems. > "mount -t tmpfs" is an easy solution that has been available widely for a > long time now. You can even allow non-root users to do it by changing > /etc/fstab. I tried running ZODB tests off of a RAM disk created that way and got lots of strange failures. :( Jim -- Jim Fulton http://www.linkedin.com/in/jimfulton _______________________________________________ For more information about ZODB, see the ZODB Wiki: http://www.zope.org/Wikis/ZODB/ ZODB-Dev mailing list - ZODB-Dev@zope.org https://mail.zope.org/mailman/listinfo/zodb-dev