Veritas-bu

Re: [Veritas-bu] FW: Multi Stream Backups

2008-11-28 13:39:41
Subject: Re: [Veritas-bu] FW: Multi Stream Backups
From: "bob944" <bob944 AT attglobal DOT net>
To: <veritas-bu AT mailman.eng.auburn DOT edu>
Date: Fri, 28 Nov 2008 13:27:40 -0500
> Both the Information Store Backup and the Mailbox Backup run 
> at the same
> time. (Not best practice, but they do). The two streams of the
> Information Store backups starts and run. The four streams of the
> Mailbox backup start but only two run and two queue. 
> 
> Summary:
> STU = 1 drive x 8 streams per drive. 
> Multiplexing of each policy's schedule = 4. 
> Allow multiple data steams = yes
> Master server global setting for "max jobs per client" = 99.
> 
> Problem:
> Although the storage unit allows 8 streams to it and the two policies
> produces 6 streams between them, only 4 run and 2 queue. Why? 
> Any ideas?

You answered your own question without realizing it--see chapter 3 of
the Veritas NetBackup System Administrator's Guide, Volume II for how
multiplexing works.  Each schedule has multiplexing set to 4.  The
storage unit setting of 8 then becomes immaterial.  The lower value
(schedule or STU) always rules.  Since there are four streams going to
the tape (two IS and two MBX, and the latter two streams are in a
schedule that allows only four streams to be multiplexed, those streams
will wait until a multiplex slot opens up.


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