Ed
Was that restores to ALL clients, or single client ?

As you say, may suit some environments, and not others (have a UNIX site
that multiplex settings were VERY low and backups took 50 hours). Increased
this setting, reconfigured the schedule and got this down to 13 hours! Also
used a 2nd tape drive.

But, may not suit everyone! I would expect restore to take a little longer
though!

I am glad for all of this input though (Ed, Paul, ect) as its nice to get a
BETTER understanding in case, as Paul quite rightly says, something goes
HORRIBLY wrong.

And at the end of the day, it can only be myself to blame. But I have not
chosen numbers out of a hat by the way :-) Care and planning and testing was
done!

Regards

Simon Weaver
3rd Line Technical Support
Windows Domain Administrator 

EADS Astrium Limited, B23AA IM (DCS)
Anchorage Road, Portsmouth, PO3 5PU

Email: Simon.Weaver at Astrium-eads.net



-----Original Message-----
From: Ed Wilts [mailto:ewilts at ewilts.org] 
Sent: 31 July 2006 12:33
To: Liddle, Stuart
Cc: WEAVER, Simon; 'Mansell, Richard'; veritas-bu at mailman.eng.auburn.edu
Subject: Re: [Veritas-bu] Multiplexing


On Sun, Jul 30, 2006 at 11:58:54PM -0700, Liddle, Stuart wrote:
> 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.

There are 2 significant factors that affect the speed the restores: 1.  How
many restores are you doing at the same time?  If it's more than
    1, then multiplexing will really hurt. 
2.  Are you doing single-file or multi-file restores?  If it's a
    single-file restore, then I don't believe that multiplexing makes a lot
    of difference (from what I've personally seen).  If you're doing a large
    multi-file restore, then multiplexing can cause a major performance hit.

I was talking to a Legato customer last week who said that he was
multiplexing 20-40 per tape and small restores could take 8+ hours.

As we always say, though, test and see what's acceptable in your
environment.  We all trade off backup times vs restore times and what's
acceptable for you may not be acceptable for me.

        .../Ed

-- 
Ed Wilts, Mounds View, MN, USA
mailto:ewilts at ewilts.org

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