1 Gb Ethernet is about 100Mb/sec
LTO4 is about 120Mb/sec + compression
A good SCSI or FC drive is good for about 100Mb/sec

Assuming you can stream 3 threads across the Ethernet, you will not be able to 
keep the 3 LTO4 drives busy because of the network.  The faster tape drives 
were not intended to take data from the Ethernet.
Assuming some sort of RAID and careful selection of file system backup times 
the disk can keep up with the network if the read is sequential and the backup 
software can find the data fast enough.
Make sure you have multiple busses.  Basically I would look for a PCI-Express 
system with enough slots for the Ethernet and RAID or HBA controllers.

I would be stressed about making the window and since you are using a 
traditional backup solution the fulls will be tough.


Andy Huebner

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
Stef Coene
Sent: Thursday, April 30, 2009 1:04 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] backup performance on intel server

Hi,

I have a non-TSM related question, but I think it is the same for all backup
software.

We need to backup 28 TB for a cutsomer with daily changes of appr 8 TB.  If
you take a backup window of 8 hr, this is 1 TB/hour.  This is also 280 MB/s
so 3,5 LTO4 tape streamers (if you take 80MB/s per tape streamer).
I can not use SAN backup, so all data has to come in over the network, so I
need at least 3 x 1 GB network connections.

What kind of intel box running windows can handle this workload?  Is the PCI
bus of a normal x86 server enough or do I need some high end x86 hardware?


Stef

PS: the backup software Backup Exec from Symantec ........


This e-mail (including any attachments) is confidential and may be legally 
privileged. If you are not an intended recipient or an authorized 
representative of an intended recipient, you are prohibited from using, copying 
or distributing the information in this e-mail or its attachments. If you have 
received this e-mail in error, please notify the sender immediately by return 
e-mail and delete all copies of this message and any attachments.
Thank you.