ADSM-L

Re: Netware restores and backup sets

2001-10-24 16:40:04
Subject: Re: Netware restores and backup sets
From: Zlatko Krastev/ACIT <acit AT ATTGLOBAL DOT NET>
Date: Wed, 24 Oct 2001 23:38:02 +0300
If creation of backupset takes only 3 hours and you think that tape is the
main limiting factor are you interested in another experiment:
Create a backupset and perform LAN-free restore. I might be faster (or may
not). If you get 3 hours (backupset creation) + 1/2 hour (tape checkout and
transportation within the building/campus) + 3 hours (local restore from
backupset) < 8 hours ?
The speed you can expect from DLT drives is ~= 5-10 MB/s (20-40 GB/hour) so
backupset restore can be easily limited not by tape but by network
performance on Fast Ethernet.

Zlatko Krastev
IT Consultant






"Richard L. Rhodes" <rhodesr AT FIRSTENERGYCORP DOT COM> on 23.10.2001 11:14:00
Please respond to rhodesr AT firstenergycorp DOT com
To:     ADSM-L AT VM.MARIST DOT EDU
cc:

Subject:        Re: Netware restores and backup sets

On 22 Oct 2001, at 23:07, Mark Stapleton wrote:
> >Is this sound reasoning?
>
> No.
>
> >Thoughts?
>
> Use some logic. A restore reads a file off of a tape and sends it
> along the SCSI/fiber connection to the TSM server, which in turn pipes
> it through the I/O bus (getting it from SCSI to ethernet/token ring),
> sends it out a network connection, through an indeterminate number of
> pieces of network hardware, gets it to its intended target. The target
> box then sends the file through *its* I/O bus to IDE/SCSI, and finally
> onto disk.
>

That's the exact point I'm interested in - just how fast can the TSM
server access all the active files for a client off of tape.  This
takes out all the stuff you mentioned.  In this case, the TSM server
can read all the files for this client in 3 hours, but an actual
restore takes 8 hours.  This means the bottleneck is not the TSM
server - it's the network and/or the client system.  In fact, the TSM
server may be able to access all the files even faster - the backup
set writes may have slowed it down.  If our Netware admins are
unhappy with the restore performance, the problem is on their side,
not the TSM server side.

Rick
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