Problem about the Performance of Disk Persistence

hello everyone,
may I ask a question about the disk persistence performence of Couchbase here?
when I use CouchbaseClient.add(String, Object, PersistTo.MASTER) to save items,
the speed is only less than 100 items per second.
the Object I’m saving is just a short string.
is this the general performence of Couchbase server?
could anyone help me~


btw: I’m using Couchbase server 2.2 and java client.

is this per node or cluster? can you also share HW profile with the topology for the cluster?