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Slow NDMP Backups on Netapp


We are having some problems with a recently implemented NDMP Netapp backup with Networker. The backups are running really slowly, between 500kb/s to 20mb/sec at best to LTO4 drives.. I suspect this is because of the number of files on each volume, they are mail spools and web hosting volumes so they contain millions of tiny files.

I have a few ideas on how to fix this, but was hoping for some advice as I am new to both NDMP and Netapp devices..

DAR backups? I've seen this mentioned in the documentation but the details are very sketchy and I'm not sure if it will help the backup speeds. I'm also concerned about what other impact it may have on the backups.

Multiple streams? We get around the dense filesystem issue on our primary file server by running parallel save sets of different folders, but with NDMP we can only run a single stream. I read somewhere that we can still use an NDMP copy to the networker server which can then multiplex onto tape with 4 streams per filer head? I believe this is configured by setting the networker server as the storage node under the Filer client, and appending -M to the nsrndmp_save command..

SnapImage? Again, the documentation is really sketchy around this but from what I have gathered, this will create a snap, then rip down the raw partition at block level so it should be really fast as the file system isnt taken into account. Our Networker support provider said this: "snapimage used ndmp, so no, you wouldn’t gain any advantage." but I don't believe it based on what I have read so far. Unfortunately I don't have the experience to say otherwise..

Any other suggestions would be really helpful but I'd like to know what you guys think.


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