Bucket creation error through REST API

Tried to created a bucket with 3000M quota on a two node cluster thru REST API:

First trial failed with the following return error: ("free" ram showed 0)

ramQuotaMB: 3000, status: False, content: {"errors":

{"ramQuotaMB":"RAM quota specified is too large to be provisioned into this cluster."}

,"summaries":{"ramSummary":

{"total":3145728000.0,"otherBuckets":0,"nodesCount":2,"perNodeMegs":3000,"thisAlloc":6291456000.0,"thisUsed":0,"free":-3145728000.0}

,"hddSummary":

{"total":51351605248.0,"otherData":7702740787.0,"otherBuckets":0,"thisUsed":0,"free":43648864461.0}

}}, header:

{'status': '400', 'content-length': '370', 'server': 'Couchbase Server 1.8.1-938-rel-enterprise', 'pragma': 'no-cache', 'cache-control': 'no-cache', 'date': 'Wed, 12 Sep 2012 17:52:19 GMT', 'content-type': 'application/json'}

Second tried succeeded with the following return msg:

ramQuotaMB: 3000, status: True, content: , header:

{'status': '202', 'content-length': '0', 'server': 'Couchbase Server 1.8.1-938-rel-enterprise', 'location': '/pools/default/buckets/default', 'pragma': 'no-cache', 'cache-control': 'no-cache', 'date': 'Wed, 12 Sep 2012 17:52:30 GMT'}