Will RAM exceeds the Quota usage?


#1

Hi,

I’m wondering when will Couchbase stores data into disk?
I worry that the RAM usage may exceed the quota of my bucket.

Thanks!


#2

Hello

The short answer is:
No Couchbase will not exceed the RAM Quota.

The server will raise an “Out of Memory Error”, and you can configure when this error is raised:
http://www.couchbase.com/docs/couchbase-devguide-2.0/handling-temp-oom.html
http://www.couchbase.com/docs/couchbase-manual-2.0/couchbase-admin-cbepctl-mutation_mem.html

Couchbase will save the document/value on disk asynchronously, but if the cluster cannot save it on disk (too many input for example), and you continue to send update operation, this exception will be raised.

You can find more information about the disk operation here:
http://www.couchbase.com/docs/couchbase-manual-2.1.0/couchbase-monitoring-diskwritequeue.html

Couchbase will not exceed the RAM Quota, since it will first save the data to disk before accepting new request.

If you have such exception you should look at your application (may be a small bug) or of this is “expected” due to a large volume of operation you should change the size of the cluster:

  • add RAM
    and/or
  • add new nodes to the cluster (this will not only add more RAM but also distribute the read and write to more machines)

Regards
Tug
@tgrall