Use of couchbase with ram file system

We’re using couchbase with drupal as a more robust replacement for memcache. Couchbase version 2.2.0 running on debian wheezy servers.

We’d like to turn persistent storage off, but that’s not an option with couchbase buckets, and couchbase buckets are required for redundancy.

The couchbase servers are busy enough writing logs and storing data that the servers are spending 20-50% of their time waiting on IO.

I tried to get around that problem my mounting a ram based file system (tmpfs, memory file system) under the /opt/couchbase/var/lib/couchbase/data/default. This produces a very odd result:

Once a client writes to the cluster, one data file in the data/default directory simply keeps growing over time. It’s a different file each time, probably dependent on what data is written or in what order it’s written. I’ll have 50 items stored in the bucket and a 32 GB data file on each member of the cluster.

Compacting the bucket does not reclaim the space.


Is there a way to use a ram based file system for performance?

Is there a way to turn off persistence?

Is there a better way to implement robust memcache compatible cluster for drupal?


— David