At 8:17 am -0800 27/11/06, Darren Dunham wrote:
>  > So what happens on the drive side if I have MPX set to 3 and then start a
>>  backup of 2 clients that can push data fast and 1 client that are really
>>  slow?
>>
>>  Is it the slow client that decide the speed of the drive then and make it
>>  stop/rewind/paus etc. and the other clients have to wait for the slower one?
>>
>>  Thanks and regards,
>
>Good question.  I don't often run NetBackup with MPX, but I can tell you
>that on Networker, the slow one doesn't slow anything down and I expect
>the same is true on NetBackup.  There it's just buffering data from the
>clients.  If one client is slow, it doesn't contribute as much to the
>buffer, but that doesn't affect the overall throughput much.
>
>--
>Darren Dunham                                           ddunham at taos.com
>Senior Technical Consultant         TAOS            http://www.taos.com/
>Got some Dr Pepper?                           San Francisco, CA bay area
>          < This line left intentionally blank to confuse you. >


That's my experience as well, the fast ones go quickly and the slow 
ones don't. The slow ones don't impact the fast ones (as a first 
approximation). We multiplex a lot (32). This allows data to be fed 
to the tape as quickly as possible, even if some of the clients are 
slow. We still tend to get one or two slow clients at the tail end of 
the backup of course, but there's little we can do about that. The 
worst example was when we had some networking issues, and one client 
was going at all of about 100kBps. That was painful.

-- 
---

REMEMBER - the safety of your data is your responsibility
If it's important to you - ** MAKE A COPY ** or 2 or 3 or 4 or ........

There is only one certainty about storage systems - they *will* fail !

Chris Freemantle
Data Manager
Wellcome Trust Centre for Neuroimaging

Tel. +44 (0)20 7833 7472 reception
Tel. +44 (0)20 7833 7496 direct
Fax  +44 (0)20 7813 1420

Home Page:  http://www.fil.ion.ucl.ac.uk