Veritas-bu

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

2008-11-28 16:32:17
Subject: Re: [Veritas-bu] FW: Multi Stream Backups
From: Jon Bousselot <jon-bousselot AT pacbell DOT net>
Date: Fri, 28 Nov 2008 13:21:34 -0800
>
>> > 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.
>
>
>   



Check the setting in the NBU java admin

Host Properties > Master Server > Client Attributes

to see what the maximum data streams is set to for that client.
If you are doing two separate policies and each policy has a max jobs
value of 4, that should let all six of them write instead of queuing
up.   If max jobs per client is really 99, you should be able to get two
policies each with a limit of 4 to get one tape drive going at 8.

If you still only get 6 going at once, maybe the remaining two streams
are not making the cutoff timeout value for other multiplexed backups to
start.  The bptm logs will show this delay when the tape mounts and
streams become ready.  
-Jon
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