Media Server Load Balancing Strategy with OST
The current version of NetBackup is attempting to balance processing load across media servers when restoring backups that used OpenStorage to duplicate backups between disk appliances. This may cause a backup that was performed on MediaServerA to DiskDeviceA, then duplicated from DiskDeviceA to DiskDeviceB, to be restored by MediaServerB if MediaServerA is already busy. In terms of load blanacing, this owuld be correct. But in terms of OST usage, when MediaServerA and MediaServerB are in two physically different locations, restoring large databases by sending them from DiskDeviceA, across the WAN to MediaServerB, and back across the WAN to the restore destination would not be appropriate.
One of the purposes of using deduplicating storage devices is to replicate data between locations, usually over a WAN, to cut duplication times and to reduce the lag between backup and duplication. The above process would make restores take far longer and introduce excessive network traffic, which would be particularly noticable over slower WAN connections.
I propose that the default behavior for NetBackup's "Media Server Load Balancing strategy" be turned off, yet easily changed for those customers that require such functionality.