Hello all,

So I've started the long path of trying to get good performance out of
my LTO3 drives.

Let me start by saying my master is Win2k SP4 running NBU MP3. The media
server is Win2k3 running NBU 5.0 MP3 with a 1 dedicated fiber channel
card for the LTO3 drive (connected through a brocade SAN switch). 

This server has 4 2tb disks coming off of dedicated HBA's from a HP disk
subsystem. I ran a multistreamed backup from 3 disks to the one LTO3
drive and was only able to get about 15mb per second per stream. This is
only about 45mb total throughput to the tape drive.

I have this message in the bptm log so I don't think increasing the
amount or size of buffers will help because it doesn't appear the server
can fill them quick enough.

 <2> write_backup_completion_stats: waited for full buffer 122203 times,
delayed 124245 times 

If I map everything out, I can see the data coming from the subsystem
switch port going to the disk HBA in the server, then going out the tape
HBA in the server and hitting the tape drive. All the numbers remain at
the 45-50mb per second.

Is this just a simple exercise of breaking my 4 2tb disks down into
smaller 500gb disks and running more streams to my tape drive? Any one
have any suggestions or watchouts?


Thanks,

Kris



-----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 stefanos
Sent: Tuesday, September 27, 2005 10:37 PM
To: Williams, Kristopher L; veritas-bu AT mailman.eng.auburn DOT edu
Subject: RE: [Veritas-bu] LTO3 Buffer Setting Recommendation

Microsoft doesn't support buffers more than 64k.
But all new fibre card's drivers can accept more buffers.
 

-----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 Williams,
Kristopher L
Sent: Tuesday, September 27, 2005 3:15 PM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] LTO3 Buffer Setting Recommendation

 
Hello,

Does anyone have a SIZE_DATA_BUFFERS / NUMBER_DATA_BUFFERS
recommendation for LTO3 on Windows2k3?

I know the first response will be to create the bptm log and try
different things. I'm just looking for maybe a good starting point to
which I will then fine tune.

Details:

NBU 5.0 MP3
HP LTO Gen 3
SAN Media Server: DL580 G4



Thanks,

Kris

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