Try and get a hold of the latest issue of Storage mag.

There's an article about performance tuning for backup-to-disk.

For one, I don't think you're doing your self any favours using
concatenated disks for your volume.

The key point in the article is to create lots of small LUNs on your
storage array, each using small chunks of space on several spindles,
then present these LUNs to your media server, and use a volume manager
on the server to create a filesystem striped acorss the multiple LUNs.

There is even a graph with some stats based on some of their test cases.

IIRC, their test bed was NBU 5.x with HDS 9570 SATA storage.

Paul

> -----Original Message-----
> From: veritas-bu-admin AT mailman.eng.auburn DOT edu 
> [mailto:veritas-bu-admin AT mailman.eng.auburn DOT edu] On Behalf Of 
> Matt Clausen
> Sent: August 10, 2005 12:44 PM
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] Fast backup to tape but slow backup to 
> disk on NBU 5.1MP3
> 
> 
> Anyone run into this? I've gotten my tape performance tuned 
> pretty well 
> under NetBackup 5.1 MP3 where I'm seeing about 
> 10,000-12,000KB/s on each 
> of my 6 tape drives even when doing a multi-streamed backup from a 
> single server. Yet when I do a backup to disk, I see decent 
> performance 
> on one stream (about 8,000KB/s or so) but the other streams 
> will drop to 
> around 300-500KB/s.
> 
> I've tweaked my buffers some following some recommendations I got off 
> the Veritas website:
> 
> NUMBER_DATA_BUFFERS = 16
> NUMBER_DATA_BUFFERS_DISK = 16
> 
> SIZE_DATA_BUFFERS = 262144
> SIZE_DATA_BUFFERS_DISK = 1048576
> 
> and I see this performance on both the master server disk pool AND a 
> media server disk pool. The master server is a VxVM concat 
> volume set of 
> 3x73GB 10,000RPM disks and the media server is an external 
> raid 5 volume 
> of 16x250GB SATA disks. I'm kinda stumped as to how to even go about 
> trying to figure out how to fix/improve the performance on this. I 
> figured that I'd be seeing the opposite where I have good 
> performance on 
> my disk drives and not so good performance on my tape drives.
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