ADSM-L

AW: Using ADSM to back-up large volumes

2000-01-12 06:34:29
Subject: AW: Using ADSM to back-up large volumes
From: sal Salak Juraj <sal AT KEBA.CO DOT AT>
Date: Wed, 12 Jan 2000 12:34:29 +0100
Hi,

you have the same problem which everybody who
cares about the aim of backup, namely restore, has.

Both major features of ADSM : 
beeing network-based 
and its incremental nature ,
have negative impact on the speed of restore.

A step back to local backups has 
another major drawbacks, thought 
the ADSM does really not have drawbacks only!

What to do with your speed?

1) your actual restore speed is not especially high.
You can try to improve it. 
We here (both NT ADSM and file servers) 
reach same slow restore
speeds from DLT tapes as you,
having definitely identified search 
times of DLT as the bottleneck.
But we reach 3 to 4 GB/hour when using 
cheap 4mm dat dds3 tapes
(however, I cannot recommend them for another, 
not performance related reasons).
We reach 10 - 12 GB / hour when restoring 
from disk storage pools.

Conclusion: 
if the CPU is your bottleneck, you have either to
upgrade it, or to change the plattform - maybe to AIX.
Having done that, the DLT tapes will likely become
your bottleneck, so you will have
to change the technology, 
maybe to either 357x or AIT.

If your 100 MBit network limits you down to 2 GB / hour, 
then there must be something wrong with your network.


2) another way to improve restoration speed might be to
upgrade the sofware to TSM 3.7.
ADSM backup/restore clients work sequentially :
request data from server, write data.
TSM 3.7 clients should do it in paralell, which should 
speed things, as long the server is able to play with.

3) check for the possibility of network backup and local restore.
The TSM can generate full-backup-like tapes on the server
(I believe they name it instant archive).
You can then move this tape to the NT server, 
and perform local restore.
Well, you would have to bue an extra tape drive which
you would have to attach to the NT server
prior to restore.
This helped only if your network were the limitation,
an this assumes your TSM server is very quick.


4) Plan to use an SAN. 
The time will come when you will be able to restore over SAN
much more rapidly then over network.

4) change the software. 
e.g. HP - Omniback
is a central managed and database based backup system.
But it allows for local tape drives , where only metainformation
is moved between backup server and backup client,
and data istelf goes to local tapes. (In fact, 
the backup client, backup server with its database and 
tape drive clients can be on three different 
computers).



Salak Juraj

KEBA AG
Softwareentwicklung Bankautomation
Gewerbepark Urfahr 14 - 16
Postfach 111
A-4041 Linz
Österreich

Tel. ++43/732/7090-7461
Fax ++43/732/730910
e-mail: sal AT keba.co DOT at
www.keba.co.at









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