Re: [Veritas-bu] Real World NBU Buffer settings Win2k3

Unfortunately I don't have much experience with buffer settings on Windows, but I have heard that Windows drivers limits the size of the buffer. I also heard that had been resolved/increased but I can't say for sure. I'm really surprised you can't get above the default (which I think is 64k?), though, that's just ridiculous.

If you try the Flashbackup and it doesn't work for you, try breaking up the normal backups into several policies/streams that will run at a time versus one long running backup.

BTW, if you ever have to restore that system (God forbid), you are going to take a hit when you go to de-mpx all that data and that will affect your SLA. Food for thought.

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"WEAVER, Simon (external)" <simon.weaver AT astrium.eads DOT net>
Sent by: <veritas-bu-bounces AT mailman.eng.auburn DOT edu>

09/15/2010 02:39 PM

To	"Martin, Jonathan" <JMARTI05 AT intersil DOT com>, "Spearman, David" <spe08 AT co.henrico.va DOT us>, <veritas-bu AT mailman.eng.auburn DOT edu>
cc
Subject	Re: [Veritas-bu] Real World NBU Buffer settings Win2k3

Jonathan
My comments about Flashbackups came from symantec rep, who felt it would not be ideal.

The volumes are "windows" compressed, and hold over 1.7TB's compressed data. Uncompressed and it could be around 3TB+
Maybe I could look into this more. But I did want to find out if anyone had buffer settings recommended for large file system backups.
Si

From: Martin, Jonathan [mailto:JMARTI05 AT intersil DOT com]
Sent: Wednesday, September 15, 2010 7:33 PM
To: WEAVER, Simon (external); Spearman, David; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] Real World NBU Buffer settings Win2k3

Actually, Flashbackup is a life-saver on Windows compressed volumes. I have a 400GB volume with 1.2TB of compressed data on it that used to take 36 hours to backup. I now move that same amount of data via flashbackup in ~3 hours.

-Jonathan

From: veritas-bu-bounces AT mailman.eng.auburn DOT edu [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of WEAVER, Simon (external)
Sent: Wednesday, September 15, 2010 2:07 PM
To: Spearman, David; veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Real World NBU Buffer settings Win2k3

Hi David
Hmmm... Thanks.
This is very interesting. And also shoots my SLA's right out of the planet into a Galaxy unknown to us!

Cannot understand how we can recover a system is 2 days, when it takes double to backup completely!

Have also mixed with Multiplexing, and no joy!

I dont think FlashBackups will help either, as its an array of small - medium - large files.

Oh dear :-(
Si

From: Spearman, David [mailto:spe08 AT co.henrico.va DOT us]
Sent: Wednesday, September 15, 2010 7:05 PM
To: WEAVER, Simon (external); veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: Real World NBU Buffer settings Win2k3
Simon,

For what it’s worth
64kb buffer size
128 buffers
Multiplex 6
LTO4
10GB backbone/2Gb FC
I have played around with all sorts of buffer sizes but in our mixed environment 64 works best.

But 4 days for 1.7TB seems more like the norm to me. We have several servers verging on 1TB that can take 36 hours.

David Spearman
County of Henrico

From: veritas-bu-bounces AT mailman.eng.auburn DOT edu [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of WEAVER, Simon (external)
Sent: 15 September, 2010 02:00 PM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] Real World NBU Buffer settings Win2k3

Hi All
Anyone got any real world experience on buffer settings:

scenarion:
Win2k3 San Media, connected to 2GB Fabric attached 8 LTO4 Drives.
Due to drive availability, Multiplexing onto one drive.

Main problem: One volume (1,7tb in size) takes over 4 days to fully complete.
Got the Tuning Guide and Technote 244602, but I tried some settings, only to find the backup would not even mount tape correctly.

So back to "no" settings at the mo.

Volume are generic files/folders, mixture of large and small sizes. But 1.7TB's in my view should be done quicker. Also Data is compressed.

Regards

Simon

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