Comment 13 for bug 1415954

The rebalancing load can be significantly decreased by limiting recovery activity in ceph.conf:

  osd max backfills = 1
  osd recovery max active = 1

This is a widely used practice to set these parameters to decrease I/O load when adding/removing nodes. The defaul values are 10 and 15, which look too high. Note, this will very likely increase the rebalancing time.

I think we should apply this solution before using more complicated.

"ceph osd set noout" is not enough to disable automatic rebalance on deployment stage. To "freez" the cluster one could

  ceph osd set noout
  ceph osd set noin
  ceph osd set noup
  ceph osd set nodown

then unset them when deployment finished and you are ready for rebalance. Gradually increasing weight technique could be used too but it might be not necessary with the ceph.conf settings above (need to check though on large deployments).