Probably the best reason for not multiplexing is that an un-multiplexed
tape can be read using gnu tar in a worst case scenario.

Patrick Whelan
NetBackup Specialist
Architect & Engineering
+44 20 7863 5243

Of all the things I've lost, I miss my mind the most! - Unknown

There are only 10 kinds of people on earth - those who understand binary
and those who don't.


-----Original Message-----
From: veritas-bu-bounces at mailman.eng.auburn.edu
[mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf Of Paul
Keating
Sent: 31 July 2006 14:16
To: veritas-bu at mailman.eng.auburn.edu
Subject: Re: [Veritas-bu] Multiplexing


Or at the very least, multiplexed to a lower value than 25.

However, if you are using fast tape and a slow network/clients, the
slowness of the clients will obscure the performance penalty of
multiplexing.

I've done some testing, and got MPX >= 10, and saw no performance hit
for backup or restores for 100Mb/s clients.....however, with high
performance clients running SAN attached disk and dedicated GigE cards
for backup, I saw significant performance hit between between MPX=2 and
MPX=3...the difference between MPX=2 and no multiplexing was negligable.

Paul

-- 


> -----Original Message-----
> From: veritas-bu-bounces at mailman.eng.auburn.edu 
> [mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf 
> Of Liddle, Stuart
> Sent: July 31, 2006 2:59 AM
> To: WEAVER, Simon; 'Mansell, Richard'; 
> veritas-bu at mailman.eng.auburn.edu
> Subject: Re: [Veritas-bu] Multiplexing
> 
> 
> Simon,
> 
> Fine....believe what you want....but the numbers don't lie.  
> 
> If you ever try any testing of this you will see that  restores are
> significantly faster when you do them from non-multiplexed tapes.
> 
> --stuart
> 


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