Never mixing NDMP and non-NDMP backup in the same media for NetWorker

The following are the limitation of NDMP backup with NetWorker.  You can find these in admin guide but most ppl tend to skip them.  It will be a nightmare when you find out data cannot be recovered.  Some of these limitation possibly apply to other backup solution as well.

For pure NDMP backup (backup to NDMP devices.  that is, FC tape drive presented to NAS), make sure you have non-NDMP backup sent to different pool including index and bootstrap.  The same applied to cloning.  So media written by NDMP devices should not be accessed by non-NDMP devies.  It is not possible to save data from any NAS filer to an tape device using standard NDMP and then write non-NDMP data to the same tape volume.  You will have issue during recovery.

NDMP and non-NDMP savesets can be saved on the same volume only if the NDMP backups to that volume were written using NDMP-DSA (NAS data backup to device presented to Storage Node / NetWorker server).

There is an old kb article from Powerlink to explain it.
"When non-NDMP backups are written to tape, the backup is written directly to the tape by NetWorker in it's own proprietary format. When NDMP and non-NDMP data is written to the same tape, the file marks get out of order and as a result the restore cannot position the tape correctly to find the data image.
Fix: Ensure that NDMP data be backed up to it's own separate pool to prevent NDMP recovery and scanner problems."

Keep in mind when migrating your NAS.  If you plan to migrate to different vendor, for ex, NetApp to BlueArc, make sure you no longer need the backup on the old NAS (in this ex, NetApp) or you keep your old NAS somewhere in case recovery required.  NetApp and BlueArc are on different OS.  That's why you cannot recover NDMP backup by NetApp to BlueArc.

Also, make sure you have a copy of the index saveset.  scanner -i does not work for NDMP backup.

For full details of limitation and other requirements of NetWorker NDMP backup, please consult EMC support or refer to EMC documentation.

NetWorker NDMP DSA performance

We try to backup Celerra VG2 using NetWorker NDMP.  From existing hardware, we decide to use NDMP DSA since we don't have license for VTL on DataDomain.  We backup 4 streams together and the total throughput is 30 - 40 MB/s.

(To find out backup performance on Celerra, logon to control station and run the following command: assuming you are backing up filesystem on Data Mover server_2)
server_pax server_2 -s -v

We contact support and they suggest us to use the -P option for the backup command where sn is the storage node you want the backup data sent to.

nsrndmp_save -T dump -M -P sn

We also list only the sn in the storage node field on the client properties of the Celerra in NetWorker.

After making the changes, we see performance improve to 100 MB/s.

Keep in mind, if you are running pure NDMP backup (that is, having a FC tape drive connected to Celerra Data Mover), the backup command will be

nsrndmp_save -T dump

i.e. For most NAS, dump is the only option supported.  Please refer to NetWorker and Celerra documentation for more info.
-M option is for DSA backup.
For pure NDMP, do not add -M in the backup command.