ADSM-L

Re: Slow Performance Restoring Large Files

2005-06-23 04:15:01
Subject: Re: Slow Performance Restoring Large Files
From: "Cahill, Ricky" <Ricky.Cahill AT EQUITAS.CO DOT UK>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Thu, 23 Jun 2005 09:14:42 +0100
I've totally run out of ideas on this and am seeking some help.

One of the systems I backup is a large SQL server, I backup the diskdumps on a 
daily basis with the largest files being aprox 110gb and 250gb.

On trying to restore large files on our DR system it starts very quickly but 
after aproximatly 10-15gb the network bandwidth slowly drops from 55% to 5% and 
on the 250gb file from 55% to currently 1%

If I copy a file from the TSM server to the SQL server I get a constant 20-25% 
with only a slight dropoff in bandwidth over time.

The nic drivers and HP load balancing software has been stripped and replaced 
with the latest. I've tried the attached storage which is defaulted to raid 5 
as raid 0 and raid 1, raid 0 made no difference to the restore times or network 
bandwidth slowdown but running in raid 1 gave 28% utilisation for aprox 70gb of 
the file before the bandwidth started slowing.

I've tried it with the sql shutdown and also with the /3gb /pae off, no 
difference.

I've also tried changing the cache on the raid card from 50/50 to 75/25 and 
100/0 write/read with now difference in restore perfomance.

The restores are coming off tape and not disk.


Specs
TSM Server      HP DL380 2gb ram 
                2xcpu 
                STK L40 with 2x LTO2 drives
                TSM 5.2.3.1
                OS WIN2k3

SQL server      HP ML570
                16gb ram
                4 x cpu
                TSM client 5.2.3.1
                OS WIN2k3


Systems connected with with load balanced 1gb network.

It looks to me like it's the raid controller and storage attached to this box 
which is slowing it down but cna't see why a copy goes trhough fine but slower 
and the restore dies over time.

Thanks in advance for any help that can be given as I'm running out of ideas.

         ...........Rikk







                


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