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NBU Multistream Selections

Created: 15 Nov 2013 • Updated: 18 Nov 2013 | 7 comments
Steven Moran's picture
This issue has been solved. See solution.

What is the impact of using filepath wildcard characters in the backup selections of a multistream enabled backup policy?

Operating Systems:

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Nate.D's picture

The impact is that it filter out what your backup selection is? I am not quite sure what you mean, I have this configuration on several production file servers. I use a NEW_STREAM directive to split up multiple 'chunks' of wildcard paths (works especially well for user directories, get all of A*, B*, C* names in a stream, D*, E*, F*, etc.

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Nate.D's picture

This has a bit more information on multistreaming.

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sri vani's picture

Multistreaming or multiple data streams is related to the number of jobs or STREAMS a policy/client can produce

u can  limit the number of jobs a Policy in the attribute column.

I have attached ref screens ..

1-3.jpg 2-1.jpg
Deb Wilmot's picture

NOTE wildcards can be dangerous.  I.e. if you have /* you could get 500 backups streams.

Be explicit in what you specified with wildcards.  It's possible that you can overload the scheduler if you have 5000 jobs all try to be initiated at the same time; OR it can slow things done substantially.

When used correctly, they are a positive thing.  

How NBU uses them?

Well - try this test:

create a test policy with /etc/* in it.  You'll get 300 or so backup streams generated.  In this case there is no control over what is separated in a stream. EVERY file and directory, directly under /etc/ will have a separate stream.

The Administrator Guide, Volume 1, has a lot more information about the effects of multistreaming.

*** My recommendation - use NEW_STREAM :)

Stumpr2's picture

Be very careful to not multistream on the same physical drive as thrashing can occur.

NOTE: This does not apply to a SAN attached drive as the drive gets mapped across several SAN drives.

VERITAS ain't it the truth?

sri vani's picture

I concur with Stumpr and Deb,

Dnt overload it..use it wisely to get positive results...