You have 6 drives for backup. All of these drives are being utilized for
writes during the backup process. During the Vault process, you have 3
drive pairs and only 3 drives are being utilized for writes (the other 3
drives are utilized as read drives). In this environment, it will take
Vault twice as long to process the backup images as it took NBU to perform
the backups. Utilizing in-line copy is similar in that you are utilizing
two physical drives for each backup, so you only have 3 active backups
running to the 6 drives (assuming non-multiplexed).
So, putting it all in perspective. If your current backup window is 7 hours
and you are using all 6 drives, it will take Vault a minimum of 14 hours to
replicate the images utilizing the same 6 drives (not including additional
time for the catalog backup nor de-multiplexing). If you are performing
in-line copy functionality, it will take a minimum of 14 hours to perform
the same task.
If you want vault to finish within the same 7 hour window above, you will
need to double the number of physical drives that you have now. Of course,
this may shrink your backup window as you have more drives to utilize during
the backup process (dependant on your environment of course). Doubling your
drives will allow in-line copy to perform both the backups and 2nd copies in
the 7 hour timeframe.
This is not a "patchable" issue with NBU, but a utilization issue of the
hardware you have.
Matthew Moody
MCSI
-----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 Darren
Dunham
Sent: Monday, April 12, 2004 3:50 PM
To: Veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Vaulting Speeds
> During the backup window the backups use all 6 of my tape drives in my
> environment.
Okay.
> Since the process to copy the tapes only leaves 3 available it
> takes twice the amount of time it took to backup the servers to do
> vaulting!
I'm not sure what you mean by "only leaves 3 available". I would
imagine that with 6 drives you copy a maximum of 3 at a time to another
3 volumes. That means you'll only have half the "bandwidth".
> After looking at the message boards it looks like others have had similar
> problems with vault speeds. Is this still true? Does it still take as
long
> to vault an image as it took to back it up?
Tape backups are often (in a tuned environment) limited by tape drive
performance. If so, duplication time should be approximately equal to
backup time. In a multiplex environment where you are duplicating a
portion of a mulitplex backup, it can be much worse.
You might want to consider in-line tape copy. If you're going to take
the time to duplicate, you might want to duplicate on the front end.
However, since it takes more drives, it would probably increase your
total backup window (while hopefully decreasing the total time that the
drives are in use).
> I'm noticing this when I look at the 'All Log Entries' for vaulting.
These
> speeds look similar to the backup speeds:
> Is there any way to speed them up? Is this fixed in ver 4.5 mp6 or 5.0
(I'm
> using 4.5 mp4 on AIX)?
Why would you expect a duplication to go faster than a backup? I'm not
certain I understand what you want to fix.
--
Darren Dunham ddunham AT taos DOT 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. >
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