|
Josef
At the moment, I have not made any buffer changes to the
system, because I wanted to get an idea of any other peoples experiences within
this environment. :-)
Hello,
I just want to mention that IBM LTO tape drives spin down
the speed. IBM LTO3 and IBM LTO4 has the same lowest speed of 30 MB/sec. And in
addition IBM LTO4 has an internal buffer of 512 MB. The mention shoe shine or
start/stop effect will (normally) not influence your backup / restore speed.
Have you the same tuning parameters
for LTO3 and LTO4, like buffer size and numbers of buffers?
Mit freundlichen Grüßen / Kind regards
Josef
Weingand
IT Specialist
STG Technical Sales Systems
Storage
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| From:
| Rusty.Major AT sungard DOT com
|
| To:
| Ed Wilts <ewilts AT ewilts DOT org>
|
| Cc:
| "WEAVER, Simon \(external\)"
<simon.weaver AT astrium.eads DOT net>, veritas-bu AT mailman.eng.auburn DOT edu,
veritas-bu-bounces AT mailman.eng.auburn DOT edu
|
| Date:
| 07.04.2009 22:10
|
| Subject:
| Re: [Veritas-bu] LTO4 Performance With
Exchange 2003 IS Poor |
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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Sent by:
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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
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