If you perform a rebalance while a node is undergoing index compaction, you may experience delays in rebalance. There is REST-API parameter as of Couchbase Server 2.0.1 you can use to improve rebalance performance. If you do make this selection, you will reduce the performance of index compaction which can result in larger index file size.

To make this request:

wget --post-data='rebalanceMovesBeforeCompaction=256' 
--user=Administrator --password=pass http://lh:9000/internalSettings

This needs to be made as POST request to the /internalSettings endpoint. By default this setting is 16, which specifies the number of vBuckets which will moved per node before pausing all moves, which will then trigger index compaction. Index compaction will not be performed while vBuckets are being moved, so if you specify a larger value, it means that the server will spend less time compacting the index, which will result in larger index files that take up more disk space.