Rebalance is slow when indexing/compaction and query load are going on in parallel

Cluster information:

• 8 centos 6.2 64bit server with 4 cores CPU
• Each server has 32 GB RAM and 400 GB SSD disk.
• SSD disk format ext4 on /data
• Each server has its own drive, no disk sharing with other server.
• Cluster has 2 buckets, default (11GB) and saslbucket (11GB) with consistent view enable. For 2 buckets, we use only 68% total RAM of system.
• Load 12 million items to saslbucket and 45 million items to default bucket. Each key has size from 512 bytes to 1500 bytes
• Each bucket has one doc and 2 views for each doc (default d1 and saslbucket d11)

• Create cluster with 4 nodes installed couchbase server 2.0.0-1746

10.6.2.37
10.6.2.38
10.6.2.39
10.6.2.40

• Data path /data
• View path /data

• Let load running at 6K ops, query 400 to 500 per second
• Add 4 nodes to cluster and rebalance
  10.6.2.42
  10.6.2.43
  10.6.2.44
  10.6.2.45

• rebalance hang. Filed bug MB-6706
• Try rebalance again. Cluster rebalances saslbucket first and took 9 hours to complete rebalance saslbucket
• default bucket took 32 hours to complete

Link to collect_info of all nodes https://s3.amazonaws.com/packages.couchbase/collect_info/orange/2_0_0/201209/8nodes-col-info-1746-reb-slow-constn-enable-20120925-141314.tgz

Each atop file size from 1.5 GB to 2.5 GB. If atop file needed, I will upload them as request