[GLLUG] SCSI bus configuration

[Melson, Paul]

A PERC3 controller can achieve peak burst rates of 160MB/s (it's
Ultra160, so duh, right?) on each channel.  So, in theory, it shouldn't
be a problem at all.  And, personally, I don't see the controller being
a bottleneck.  

The thing that occurs to me, though, is that your loader may be
differential SCSI (very common w/ tape loaders & robots for AIT and DLT
drives) and require a different controller altogether.  

PaulM

-----Original Message-----
From: Edward Glowacki [mailto:glowack2@msu.edu]
Sent: Wednesday, June 05, 2002 4:37 PM
To: linux-user@egr.msu.edu
Subject: [GLLUG] SCSI bus configuration


OK, this has been bothering me for a bit, so I thought I'd ask the
group.  

Assume the following setup for a tape backup server:

100Mb or gigabit network interface
A RAID controller (Dell PERC3-DC [AMI MegaRAID])
3x 18GB SCSI3 (U160) disks in RAID 5 (internal)
2x AIT3 tape drives (31MB/s max rated speed) in a tape loader (external)

The RAID card says its "dual channel - 1 internal, 1 external".  The
disks are going to probably be getting hit hard as the backup software
updates its database, and the tapes will hopefully be receiving a good
flow of data, assuming the network and the client machines can keep up. 
Is having all this on one controller going to produce any performance
problems?  I'm assuming it should be fine in this setup, but I'd like to
go in with at least some idea if there might be a problem lurking... =)

Thanks!

-ED

-- 
Edward Glowacki				glowack2@msu.edu
GLLUG Peon  				http://www.gllug.org
Imagination is the one weapon in the war against reality.
                -- Jules de Gaultier

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