Best Practices Procedure to reclaim disk space? vacuum?

I have a 4 node cluster running 1.8.1

Over time I see my disk usage climbing and climbing. What is the best procedure to clean things up. I tried vacuum, but I get the following:

Traceback (most recent call last):
File "/opt/couchbase/lib/python/cbdbmaint", line 88, in ?
main()
File "/opt/couchbase/lib/python/cbdbmaint", line 65, in main
db_path = mc.stats()['ep_dbname']
File "/opt/couchbase/lib/python/mc_bin_client.py", line 311, in stats
cmd, opaque, cas, klen, extralen, data = self._handleKeyedResponse(None)
File "/opt/couchbase/lib/python/mc_bin_client.py", line 89, in _handleKeyedResponse
cmd, errcode, opaque, cas, keylen, extralen, rv = self._recvMsg()
File "/opt/couchbase/lib/python/mc_bin_client.py", line 71, in _recvMsg
raise exceptions.EOFError("Got empty data (remote died?).")
EOFError: Got empty data (remote died?).

All nodes are in fact up and processing traffic, but a disk space issue is clearly looming.

Any help would be really appreciated.

G