On Wed, Aug 3, 2011 at 4:54 PM, Les Mikesell <[email protected]> wrote:
> > Are you confusing membase with memcache? The former is a persistent, > replicated store, or at least that is the claim; the latter a cache. > http://www.couchbase.org/wiki/**display/membase/Membase+**Architecture<http://www.couchbase.org/wiki/display/membase/Membase+Architecture> > > -- > Les Mikesell > [email protected] > > > Les, You are right, I was thinking of memcached when I wrote that reply. However, I don't know if that changes much of what I said. Looking at membase docs [1,2] it is essentially a drop-in (they use the term "OTC" for Over The Counter) replacement for shops traditional memcached deployments but adds persistence, replication, etc (although, I thought I remember there being two different kinds of buckets in membase, one that is persisted and one that is not, what's the default?). Looking at the vbucket literature it sounds to me as if replication is something you decide to add, not on by default [2]. Furthermore, it's a master/slave replication strategy which is different from Riak's quorums. For example, when doing a read against Riak with N=3 it will _always_ contact 3 vnodes even if you set R=1 (it just won't wait for all 3 replies). Contrast that with membase which will only perform a read from the master which will be less expensive because you don't have to perform coordination on the replies. For a membase deployment to kinda look like a Riak one it should have 2 replicas using a one-to-many strategy (as well as being persisted to disk). I'd be interested to see how the two would compare but now I'm drifting off topic a bit. -Ryan [1]: http://www.couchbase.org/wiki/display/membase/vBuckets [2]: http://dustin.github.com/2010/06/29/memcached-vbuckets.html
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