Veritas-bu

[Veritas-bu] Limit a class to a number of drives

2001-11-28 14:09:40
Subject: [Veritas-bu] Limit a class to a number of drives
From: larry.kingery AT veritas DOT com (Larry Kingery)
Date: Wed, 28 Nov 2001 14:09:40 -0500 (EST)
markjessup AT northwesternmutual DOT com writes:
> I am rather new to Netbackup and have a couple of questions.
> 
> I was wondering if there is a way to have a specific class have access
> to a specific number of drives within a storage unit.  If a storage unit
> has 4 total drives, I want this class to have access to only 3 drives
> but then have a second class have access to all 4 drives in the storage
> unit.  Is this possible?  

This depends on a lot of things, including if you're using the term
"storage unit" to refer to a physical device, or a logical device like
NBU does.

If you have a ROBOT with four drives, you can configure two storage
units, one with four and one with three.  In this fashion, you can
limit certain classes to only use three.

A common usage would be to configure a single STU with only three
drives.  This way, there will (almost) always be a drive which isn't
getting used for backups (and hence is available for restores).

Note that you can't say WHICH drives apply to a single STU, only the
NUMBER.  So if in the above example a drive is down, you would still
be able to use three for backup, and none would be idle for restore.

Note that restores (and drives used for reading in duplication) don't
use STUs to read from.  They just use any drive that's available (in
the correct robot of course).

Other things which might help you are the "max jobs per class", and
possible "max jobs per client" parameters.  Use of multiplexing will
complicate things, but the right combinations of settings may allow
you to acheive your goal.

> 
> A second question is regarding class priority.  If I have a class that
> is priority of 0 and has 20 clients to backup and its backup window
> starts at 22:30.  I then have a different on demand backup that comes in
> at 22:45 and it has a class priority of 99, will this backup leap frog
> the other backups that have the lower priority that have been  waiting
> since 22:30?  

Maybe.  No jobs will stopped once they're active.  Priority only
applies to jobs in the queued state.  

I'm not sure what will happen if you're using multiplexing (will it
wait until all streams are complete for a given drive and then release
the drive for the higher priority stream - which I'm assuming can not
be mixed with the others, or will it go ahead and schedule a lower
priority job which can make use of some of the drive capability at the
moment).  You can probably ignore this paragraph if it makes no sense.

See NBU SAG appx C for more details on how jobs get scheduled.

L

> 
> Thanks!
> 
> 
> Mark Jessup 
> IS Manager, Enterprise Storage and Output Management
> Northwestern Mutual
> (414) 665-3968
> markjessup AT northwesternmutual DOT com
>  
> 

-- 
Larry Kingery 
               "What are you going to do, bleed on me?"

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