On Thu, Mar 3, 2011 at 6:42 PM, dormando <[email protected]> wrote: > > Hi all, > > I know I'll get blasted for not googling enough, but I have a quick > question. > > > > I was under the impression memcached servers replicated data, such that > if i have 2 servers and one machine goes down the data would all still be > > available on the other machine. this with the understanding that some > data may not yet have been replicated as replication isn't instantaneous. > > > > Can you clarify for me? > > > > thx, > > > > -nathan > > I sound like a broken record about this, but I like restating things > nobody cares about; > > - memcached doesn't do replication by default > - because not replicating your cache gives you 2x cache space > - and when you have 10 memcached servers and one fails... > - ... you get some 10% miss rate. > - and may cache 2x more crap in the meantime. > > if your workload really requires cache data never disappear, you're > looking more for a database (mysql, NoSQL, or otherwise). >
hmm, i hear you here and am starting to wonder about the application of memcached which drove me to this question, namely php session storage. it's often discussed on the php-general list the pros and cons of memcached in said application and i know many sites move to memcached to increase performance over a db backend. however there is the issue of loosing the session if a memcached box goes down. perhaps memcached isn't the most appropriate place for session storage as its not considered data that should be allowed to disappear. i know its OT, but .. thoughts? :) -nathan
