Simon is correct here. The speed of any drive is based on how much data your
systems are capable of sending to it. I have been involved in about 15
installs of LTO drives both SAN and direct SCSI attached and have seen
speeds ranging from really crappy to "holy cow" fast. 

I have never seen a Windows based box send a stream of data faster than
5MB/sec so you would need to send four or five streams of data from a number
of Windows machines to keep an LTO drive happy. 

Unix is another story. I have personally seen a high end E450 send 10 MB/sec
per stream and send two streams across two HBA's at that speed at the same
time for a total of 20 MB/sec. so, if you have two such machines, you could
multiplex them onto two drives for 20MB/sec per drive which should keep an
LTO drive very happy. (one stream from each machine to each drive for a
total of two streams to each drive).

LTO drives and LAN based backups where you have LAN traffic moving thru a
Media Server that is either direct attached or SAN attached require a bit
more thought. The Media Server must have at least a GbE interface that is
properly configured for full bandwidth and robust enough to handle the GbE
interface and the HBA's for the SAN. Then you have to send enough 100Mbit
streams of data to the Media Server from multiple LAN clients to keep the
LTO drive streaming. 

It is all fairly complicated but that is the beauty of NetBackup. It is
simple to configure it just to get some backups to run, but its complexity
with configurability and its ability to keep any class of tape device
streaming 100% with proper set up is incredible. 

So, that all being said, Pravin, what other systems do you have streaming
data to your drives? You have mentioned one system only on the SAN. You will
have trouble getting a single system to send much more than 20 MB/sec total
unless you have some very fast disk, multiple processors and good HBA's. at
20MB/sec total, a speed of 67 GB/hr sounds pretty close. Get two systems on
the SAN and send two streams from each of them from separate disk farms to
the same LTO drive to see if you can max it out (look in the bptm log to see
if you are maxing the drive out completely). Also, make sure your streams
(if you are running multiple streams) are not coming from the same disk
split into different slices. This will just cause disk thrashing. 

Have fun. 

d. 

_____ 
dave high
VERITAS Enterprise Consulting
Bay Area Region
702-683-7733
 
"Unix IS user friendly, it is just VERY picky who it chooses as friends" 

-----Original Message-----
From: WEAVER, Simon [mailto:Simon.WEAVER AT astrium-space DOT com] 
Sent: Wednesday, May 29, 2002 6:00 AM
To: 'veritas oracle sun'
Cc: 'veritas-bu AT mailman.eng.auburn DOT edu'
Subject: RE: [Veritas-bu] Netbackup & LTO performance

Forget it!!!!!
The client I work for sent some staff off to a seminar to talk about LTO.
They were told of GREAT speeds and HUGE compression capability!
 
What they forgot to mention is that it all depends on:
 
Your LAN / WAN
Hardware Configuration
Amount of Data (small files are a killer)
Compression!
 
We don't get the specs we were quoted! I don't think many people do!
 
Simon Weaver
NT Domain Administrator
Ext. 5544
Tel: 02392-705544 (Direct Dial)
Simon.Weaver AT Astrium-Space DOT com
 
-----Original Message-----
From: veritas oracle sun [mailto:vos2002 AT indiatimes DOT com]
Sent: 29 May 2002 11:42:AM
To: NB
Subject: [Veritas-bu] Netbackup & LTO performance
 
Hi all
Currently we are doing testing of HP Ultrium Drives 
We are using SAN env. to perform backup 
Netbackup is configured on Solaris 8 & NBU 3.4 Datacenter
As per LTO specification 100GB/Hrs is minimum speed
But I am getting on 67GB/HRS in SAN env.
I did tunning Buffer Size Number of buffer and /etc/system shared memory
parameters
but no improvement
If any one achive above speed pls mail me configuration done @ your end
Thanx & Regards
 
Pravin Kudav
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