System architecture best practices - memcached + webfarms
rj at last.fm
Mon Jul 2 21:57:43 UTC 2007
I've been thinking about what changes we may have to make to our memcached
installation in future as we continue to grow - our webfarm is approaching
100 servers, each with 4GB ram, ~2GB of which is dedicated to memcached on
As we add more nodes, the usefulness of get_multi decreases - it's possible
for a single page to hit almost all of the memcached instances. I read
somewhere that facebook partition their memcached cluster to improve
get_multi performance (eg, all user data on a subset of mc nodes). Can anyone
comment on the effectiveness of this?
Are we fighting a losing battle here - perhaps we should try and cram as much
ram as possible into a small number of machines (what do you do?). get_multi
would be more useful, but it costs more and doesn't seem as elegant :(
Can anyone comment on how many memcache lookups they make per page?
Traditionally our developers treated memcache lookups as "free", but when
you're doing a few hundred memcache gets per page it soon adds up..
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