Multiple Streams 1

[hatman]

On my file server I would like to enable streaming. I don't like the 'automatic' way netbackup makes 1 stream per drive because most of my data lies on E: so the E: stream takes forever.

My E: drive has a folder we'll call Data. I want that to be 1 stream, and everything else (all other folders on E: *and* the C: drive) on another stream, basically splitting the data load. Is there any way to do it other than manually naming EVERY other folder on E: in the File Directive? I read you can't do a NEW_STREAM "AND" a ALL_LOCAL_DRIVES.

I thought possibly:
NEW_STREAM
E:\DATA
NEW_STREAM
ALL_LOCAL_DRIVES

Any help would be greatly appreciated. Thanks!

 

[comtec17]

You cannot do a the New_Stream Directive and ALL_LOCAL_DRIVES together. You could create 2 classes with 1 backing up only the E:\Data and the other backing up all other files and putting an exclude list together to use with the 2nd class and exclude E:\Data.

 

[hatman]

1st, thanks for your response!
But this brings up other questions: I tried this last night, but my throughput was dropped down from 14kb/s to 8 or 9kb/s. Is this because I'm trying to backup data on the same drive of the server (drive e:\data and c:\ & e:\"EVERYTHING ELSE&quot at the same time? I believe that NB admin books kind of frown on this backing up from the same "physical drive" at the same time. Should I do e:\data at the beginning of the night and c:\ & e:\ "Everything Else" toward the end to stop the 'same-time same-drive' reading & writing?

Currently, I've got e:\data listed in my directive list on ClientA and ALL LOCAL DRIVES listed on CLIENTB with e:\data in the exclusion list (no "new_stream" listing in either directive list). Since the throughput has declined, the backup(s) are actually taking about 30 minutes longer. Any suggestions? Thanks!

 

[Charles]

Other than creating Multiple policies to multi-stream one mount point, just multiplex the job to 3 or 5... Of course you allways pay in the backend with slower restores....

 

[comtec17]

It is recommended by Veritas to use 1 stream per physical volume since using multiple streams will cause disk thrashing and tape shoeshining. I would let your largest job run first and have the other jobs run when the 1st job is complete.

 

[johnny99]

I think the only reason why Veritas default to 1 stream per drive when using ALL_LOCAL_DRIVES is because that is fairly easy to describe.
If they started to try to define automatic rules they that should find the "best" multiplexing on all server combinations, with all drive combinations, with all data combinations they would end up with some programming that would make a chess program look like a schoolboys programming.

But must people have to use multiplexing to get any real use out of multistreams, since most of us have a lot less tapedrives then logical disks we want to backup.

Multistreaming in it self doesn't have very much impact on tape shoeshining except when you hit the limit of the disksubsystems / network compared to what the drive needs.
Some drives also have bigger problem with tape shoeshining then others. DLT is a hell and STK9940B isn't.

Multiplexing can help you to have less problems with tape shoeshining.

By the way, it's multiplexing that hurt you on restores not multistreaming.