Netbackup NDMP backup low deduplication

[dsk1]

Hi,

We are on Netbackup 7.7.3 using MSDP as the backup target. Some of our NDMP backups are giving poor deduplication ratio less than 10% that is causing storage full condition. Can someone suggest what needs to be verified to check the root cause. Some of the reasons that could impact deduplication I know of are

1) Compressed data 2)Encrypted data 3) Dedup data on filer end.

Can someone suggest what else needs to be verified to know the root cause of poor deduplication for NDMP.

[Nicolai]

What options are set for the NDMP backup ? (e.g: set type=tar or dump)

Who is the venfor of the array, EMC/HDS ?

[watsons]

There used to be a performance problem with NDMP data going into MSDP pool, this was the technote:

http://www.veritas.com/docs/000083600

It mentioned about deduplication rate as well, along that line with stream handler. As far as I know, for different NAS vendors, the handler could act in a way that impacts dedup rate. 

If you have already done your due diligence, confirming that other policy types are having good dedup rates except NDMP, enable pdplugin logs (on MSDP side) and log a support call for analysis.

[dsk1]

The Filer is Dell compellent FS8600 running on FluidFS 5.0. Also compression and deduplication is enabled on the volumes on Filer. There is not option selection in backup selection, so it is defaulting to DUMP.

[Marianne]

So, you know exactly why you are getting poor dedupe rates.
These types of data are not good candidates for MSDP or any kind of dedupe storage.

You will be better off backing this up straight to tape.