In my previous life as a SysAdmin, I was seeing 7MB/s during vaulting of MPX
tapes (4-way MPX) using DLT7k's.  Using STK 9840a's I was seeing 15MB/s with
20-30MB/s peaks during the replication of the 2GB tape fragments (watching
bptm log).  In both of these scenario's, I was demultiplexing the backups.
In the case of the 9840 drives, I was actually replicating the tapes faster
than I was able to back them up. (AIX RS6k 4-way, 4GB memory, direct
attached DLT's with fibre-switched 9840a's).

All backups that were slow (network), were required to utilize MPX.
Demultiplexing for replication was required to ensure quick recovery in case
of DR utilizing off-site media.  I found sending MPX replications off-site
to not be in the best interest of the company I worked for at the time since
a full restore from MPX tapes require 10x the timeframe (per stream) of
non-MPX backup images (per NBU doc).  Using a 4-1 MPX would take 40x longer
to perform a restore from off-site tapes.  Not acceptable.....

For reference, if you utilize 4 tape drives for backups and those backups
require 8 hours to complete, replication of those images will require at a
minimum 16 hours to complete assuming the replication speed is at least as
fast as the backups.  Throw in MPX backups and the timeframe can conceivably
be extended. To fix this issue, you can throw more tape drives into the mix
and NOT run MPX backups or, of course, fix the speed issues.  If you have
not "tuned" the environment, I suggest you jump onto the Veritas website and
download the tuning guide to tune your buffer settings, etc.

Good luck.  These are never fun issues to resolve...

Matthew Moody

-----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 Shafto,
Eric
Sent: Monday, January 27, 2003 12:37 PM
To: 'Kennedy, Jeffrey'; Deb; Zink, Melanie
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Considering moving to NetBackup


I'm routinely seeing 7-8 Kbytes/sec on DLT 7k's with under-resourced media
servers.

But I don't demux...

-----Original Message-----
From: Kennedy, Jeffrey [mailto:jkennedy AT qualcomm DOT com]
Sent: Monday, January 27, 2003 1:27 PM
To: Deb; Zink, Melanie
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Considering moving to NetBackup


Slow as in sloooooooowwwww.  When I tried vaulting from tape to tape
with original backups using a 6 MPX, I was seeing kb/sec transfer rate.
No matter what I did, or Veritas tech support had me try, I got a
maximum transfer rate of 700kb/sec.  Not really feasible in today's data
center.

But that could have just been me.  Tech support seemed stumped.

~JK

> -----Original Message-----
> From: Deb [mailto:deb AT tickleme.llnl DOT gov]
> Sent: Monday, January 27, 2003 8:13 AM
> To: Zink, Melanie
> Cc: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: Re: [Veritas-bu] Considering moving to NetBackup
>
> Zink, Melanie <Melanie.Zink AT bankofamerica DOT com> had this to say,
>
> > Be aware, however, that vault itself is slow, and de-mux slows it
down
> even further.....
>
> Really?!?  Please, How do you define slow?  How much data over how
> much time for vault?  De-mux?
>
> deb
>
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu

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