|
Not at all Rusty :-)
The disks are on a high speed HP EVA system, so I know they
are not the problem. I am happy now that the backup has returned back to its
"normal" speed, but I think alot of it does also depend on the type of Data you
do backup, and whether you get the performance.
ie: Streaming a large single DB file is always going to be
quicker for the drive to handle, compared to thousands of various type of files
and folders of varying sizes.
Simon
Very nice break down, Ed. This type
of situation is where the need for disk storage units becomes more and more
apparent. It's getting harder and harder to stream at the speeds faster tape
drives need to stay running at an acceptable level.
Just because the drive CAN go faster doesn't mean it
WILL, all other things remaining the same.
Not a knock on you, Simon.
Rusty Major, MCSE, BCFP, VCS ▪
Sr. Storage Engineer ▪ SunGard Availability Services ▪ 757 N. Eldridge Suite
200, Houston TX 77079 ▪ 281-584-4693
Keeping
People and Information Connected® ▪ http://availability.sungard.com/
P Think before you print
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Ed Wilts
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Sent
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04/07/2009 10:19 AM
|
|
To
| "WEAVER, Simon (external)"
<simon.weaver AT astrium.eads DOT net>
|
|
cc
| veritas-bu AT mailman.eng.auburn DOT edu
|
|
Subject
| Re: [Veritas-bu] LTO4 Performance
With Exchange 2003 IS Poor |
|
On
Tue, Apr 7, 2009 at 8:12 AM, WEAVER, Simon (external) <simon.weaver AT astrium.eads DOT net>
wrote:
Environment:
NBU 5.1 MP5 Master Plus
many SAN SSO Media Servers Win2k3 SP2
Problem: Mail Backups of Information Store
using LTO4 SL500 are taking 4 1/2 hours extra to backup compared to LTO3.
If the tape drives were not your bottleneck before - i.e. you
were continually driving them at least 80MB/sec, then upgrading to LTO-4
will likely slow your backups down. By my calculations, you weren't
bottlenecked at the tape drives. You were taking 4 hours for 1TB of data.
That's a total of 69MB/sec. If you were doing that to 3 drives, you were
only averaging 23MB/sec per drive.
LTO drives must stream. If you
can't feed them data fast enough, you'll shoe-shine the drives with continuous
start/stop fashion and performance will suck.
Same configuration is in place (ie: 3 streams to 3 different
drives) and all part of the same fabric, apart from being in a different
building.
An IBM LTO4 drive requires a MINIMUM of 30MB/sec. An
HP LTO4 requires a MINIMUM of 40MB/sec. That's assuming no
compression. If you're compressing with a 2:1 ratio, you'll need double
that. They top out at 120MB/sec native and 240MB/sec with (2:1) compressed
data.
So let's assume 2:1 compression on 3 streams going to an HP
drive. You'll need to deliver 2*3*40MB/sec, or 240MB/sec at an absolute
minimum. You can deliver up to 2*3*120 or 720MB/sec.
Since you were only averaging 23MB/sec per drive before, you've
got a LONG way to go.
.../Ed
Ed Wilts, RHCE,
BCFP, BCSD, SCSP, SCSE
ewilts AT ewilts DOT org_______________________________________________
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