Let me correct myself, "less likely to push multiple streams of data 
sufficiently to the media server"

sorry about that, the word 'sufficiently' was implied in my mind, but as I re-
read it I was concerned that it wouldn't have been by others.

David

Quoting "David A. Chapa" <david AT datastaff DOT com>:

> WORD TO THE WISE:  Do the math before you set your MPX value...What is your
> 
> network speed, what is your drive speed, how many MPX before you start seeing
> 
> diminishing returns.  If you are sending too many MPX streams to the drive
> you 
> will end up with WAITING FOR EMPTY BUFFERS in your bptm log on your media 
> server, thus meaning that your drive can't keep up.  Alternatively speaking
> if 
> you have WAITING FOR FULL BUFFERS, then perhaps you can increase your MPX 
> value, but remember balance is the key when you look to tune your
> environment.
> 
> Dave:  The question about streams, it would depend if he has implemented MDS
> 
> (Multiple Data Streams), if he had, then each Drive would potentially be an
> 
> individual stream.  
> 
> Simon: This would only be a potential problem if you have modified the
> default 
> value (1) MAX JOBS PER CLIENT to > 1.  If you do that, you really need to be
> 
> careful.  Its been my experience that NT/2000 (single processor Intel boxes)
> 
> are less likely to push multiple streams of data to the media server.  Your
> 
> mileage may VARY box to box...
> 
> David
> 
> Quoting David Markham <dave.markham AT icl DOT net>:
> 
> > I think you should set it to 8 if you want all clients to backup to 1
> tape,
> > and watch what happens. I've  just had a thought which someone may want
> to
> > clarify. As there are 2 drives beeing backed up does that mean theres 2
> > streams per client, or just the 1 for the job?
> > 
> > If its the first then you may need to set the mpx to 16 to get the
> schedule
> > to backup to one drive.
> > 
> > Dave
> > 
> > -----Original Message-----
> > From: WEAVER, Simon [mailto:Simon.WEAVER AT astrium-space DOT com]
> > Sent: 21 May 2002 06:24
> > To: 'dave.markham AT icl DOT net'
> > Cc: veritas-bu AT mailman.eng.auburn DOT edu
> > Subject: RE: [Veritas-bu] Multiplexing
> > 
> > 
> > Thank you all,
> > So Dave, if I have a Backup Policy with 8 clients and they all backup the
> > C:
> > Drives and E: Drives, what Multiplex number should I use? At the moment I
> > have set it for 4 to see what happens.
> > 
> > Thanks
> > 
> > Simon Weaver
> > NT Domain Administrator
> > Ext. 5544
> > Tel: 02392-705544 (Direct Dial)
> > Simon.Weaver AT Astrium-Space DOT com
> > 
> > -----Original Message-----
> > From: David Markham [mailto:dave.markham AT icl DOT net]
> > Sent: 20 May 2002 03:19:PM
> > To: WEAVER, Simon; 'Dave High'
> > Cc: veritas-bu AT mailman.eng.auburn DOT edu
> > Subject: RE: [Veritas-bu] Multiplexing
> > 
> > Yes if they are backed up from the same schedule, and they use tapes all
> > from the same pool.
> > 
> > You will need to make sure the max mpx per Drive is set higher than 2
> also.
> > 
> > Dave
> > 
> > -----Original Message-----
> > From: veritas-bu-admin AT mailman.eng.auburn DOT edu
> > [mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu]On Behalf Of WEAVER,
> > Simon
> > Sent: 20 May 2002 14:56
> > To: 'Dave High'
> > Cc: 'veritas-bu AT mailman.eng.auburn DOT edu'
> > Subject: RE: [Veritas-bu] Multiplexing
> > 
> > 
> > Hi Dave / Everyone
> > My apologies, I probably did not make myself clear.
> > 
> > Yes I am not looking for a way to put more data onto the tape (Obviously
> if
> > it his its 100GB Limit, it will get a new tape and I fully understand
> > that).
> > But I think the point being made is that I want these 8 clients to
> utilise
> > one tape until it is full, and then move onto another tape.
> > 
> > Here is my point. We have a lot of jobs with a lot of clients (16 per
> > backup
> > policy) and they have a lot of streams. I just wanted to clarify that if
> I
> > increased the multiplexing number from 2 to a higher number, would
> > Netbackup
> > try to place the Data onto the same tape in a single drive? At least
> until
> > the tape becomes full :)
> > 
> > Simon Weaver
> > NT Domain Administrator
> > Ext. 5544
> > Tel: 02392-705544 (Direct Dial)
> > Simon.Weaver AT Astrium-Space DOT com
> > 
> > -----Original Message-----
> > From: Dave High [mailto:Dave.High AT veritas DOT com]
> > Sent: 20 May 2002 02:37:PM
> > To: WEAVER, Simon; 'veritas-bu AT mailman.eng.auburn DOT edu'
> > Subject: RE: [Veritas-bu] Multiplexing
> > 
> > Simon,
> > 
> > Multiplexing will not help you write "more" info to a tape. A tape can
> hold
> > a specific amount of data based on tape format and compression. Once it
> is
> > full, it is full. Using Multiplexing can help you use less tapes during a
> > backup run since more streams are filling up a single tape rather than
> > loading three tapes and writing to them, but NetBackup will continue
> > loading
> > and using a tape until it is full, then it will move on to a new tape.
> > 
> > Also, on other thing I wanted to point out about the bpexpdate command is
> > that it does NOT "erase" a tape it simply removes the NetBackup Catalog
> > reference to that tape and allows it to be overwritten. The data is still
> > on
> > the tape until it is overwritten. The only reason I bring this up is for
> > security reasons. If you need to get rid of the data on the tape, you
> need
> > to bpexpdate it, then run a big magnet over it to wipe the data.
> > 
> > Hope this all helps.
> > 
> > dave
> > 
> > -----Original Message-----
> > From: WEAVER, Simon [mailto:Simon.WEAVER AT astrium-space DOT com]
> > Sent: Monday, May 20, 2002 5:45 AM
> > To: 'veritas-bu AT mailman.eng.auburn DOT edu'
> > Subject: [Veritas-bu] Multiplexing
> > 
> > Firstly, Thank you all for your help with BPEXPDATE. I am glad I am
> getting
> > this right now :)
> > 
> > I have one small question about Multiplexing. On the Netbackup PDF's
> (which
> > is what I am using) it says you can specify the number of jobs that can
> > multiplex to a single tape drive! (Words to that effect).
> > 
> > My question is this: I have a backup policy with 8 clients listed. Within
> > this backup policy I have specified to backup All Local Drives for these
> 8
> > clients. I want to use as less tapes as possible (I use 100GB HCART
> Tapes).
> > If I increase this Multiplexing number, does it mean that more data will
> be
> > written to a single drive in a tape?
> > 
> > We use an ADIC Scalar 100 which consists of 3 tape drives. Because I have
> > no
> > more slots available to place blank tapes, I was kind of hoping that
> using
> > this Multiplexing option will help retain more data on a single tape!
> > 
> > Am I right, or am I reading this incorrectly.!
> > 
> > Thank you
> > 
> > Simon Weaver
> > NT Domain Administrator
> > Ext. 5544
> > Tel: 02392-705544 (Direct Dial)
> > Simon.Weaver AT Astrium-Space DOT com
> > 
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> > Gunnels Wood Road
> > Stevenage
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> > or otherwise deal with it.  Please notify the sender by return email.
> > The views of the author may not necessarily constitute the views of
> Astrium
> > Limited.
> > Nothing in this email shall bind Astrium Limited in any contract or
> > obligation.
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> > Gunnels Wood Road
> > Stevenage
> > Hertfordshire
> > SG1 2AS
> > 
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> > 
> 
> 
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