Data balancing fails on MOngo cluster with 1 mongos and 3 mongods.. All the data for the collection fs.chunks stays in the same shard with the following error.

Env: Ubuntu- AWS m3.large,

error from sh.status()

6 : Failed with error 'could not acquire collection lock for test.fs.chunks to migrate chunk [{ : MinKey },{ : MaxKey }) :: caused by :: Lock for migrating chunk [{ : MinKey }, { : MaxKey }) in test.fs.chunks is taken.', from shard0001 to shard0000
3826 : Failed with error 'moveChunk failed to engage TO-shard in the data transfer: can't accept new chunks because there are still 7 deletes from previous migration', from shard0000 to shard0001
7655 : Failed with error 'moveChunk failed to engage TO-shard in the data transfer: can't accept new chunks because there are still 4 deletes from previous migration', from shard0001 to shard0000