We're using Backup Exec 2010 R3 sp3 to backup a CIFS share on a volume using NDMP backup.
The volume is located on a FAS3270, ONTAP ver. 8.1.2, SAS disks.
The backup is going to a volume on different controller (FAS3210) which contains only sata disks.
The thing is that everytime the jobstarts, it can hang for 2 hours without backing up anything (no jobrate and bytes count is displayed) and than it suddenly kicks in. The jobrate is very slow, around 300MB/min, but that be due to the slow SATA disks.
We tried to backup another volume which contains a LUN and the backup started right away. The job rate was very good (around 5,000MB/min) but it was to tape, not to disk.
Why is the CIFS backup hangs for so long before it starts to actually backup?
Initial stage of NDMP backup is file scanning. The more files there are on a volume, the more time it takes. There is usually nothing that can be done except using block based backup (like SMtape) if supported.
If you are using another NetApp to store backups, it would make more sense to use SnapVault for it directly.
SMtape is “SnapMirror to tape” - it is block based copy of the whole volume to tape. It is more efficient than file based NDMP (actually, dump); downside is, you can restore only the whole volume, not individual files. So it is more a disaster protection than day to day backup. I know that NetBackup supports it; cannot say about BackupExec.
SnapVault is NetApp “incremental forever” replication between two volumes. It is block based so is not affected by number of files. It transfers difference between previous and current snapshot to destination and optionally creates snapshots on destination side. But it requires extra license.
SnapMirror is intended for replication and SnapVault for backup. You can use SnapMirror to achieve the same as SnapVault does, it just automates several steps making it more convenient. Also you can revert SnapMirror but cannot revert SnapVault. You can read more in NetApp documentation.