>
>> >
>>     
>>>> >> > 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
>   



Wait...I'll respond to my own post.  bob944 did cite the correct
reference on this one.
It took me a while to process all the values in the mix here.  If you
want both policies to run at the same time and not queue any streams,
set both your exchange policies mpx to 8 or 6, and you can keep the
limit jobs per policy to 4.  If your policies only generate 2 and 4
streams each, I don't see any value in having this limit set since the
next hard limit will be mpx on the storage unit. 

If you multiplex too high, it will cut back the restore speed of your
LTO4 drive.  I've done exchange backups and restores with MPX=8, and it
was acceptably fast for the RTO.  Be sure to make time to test this so
you aren't surprised during a real emergency.

-Jon
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