Veritas-bu

[Veritas-bu] Multiplexing

2002-05-21 03:30:22
Subject: [Veritas-bu] Multiplexing
From: dave.markham AT icl DOT net (David Markham)
Date: Tue, 21 May 2002 08:30:22 +0100
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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This email is for the intended addressee only.
If you have received it in error then you must not use, retain, disseminate
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.
Astrium Limited
Gunnels Wood Road
Stevenage
Hertfordshire
SG1 2AS


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