Summary - Adding an Additional external HD

From: April Sims (
Date: Tue Apr 18 2000 - 08:17:26 CDT

Thanks to several people: Kristopher T. Briscoe, Mike Mehran Salehi,
Adam Levin,Kevin Korb,Michael Allmen
Martin Oksnevad, Al Hopper

Most of the answers said that "SCSI is SCSI" and the hard drive should work
but with performance issues.
Two other people composed a longer answer with some additional details.
Thanks to Martin, who pointed out that an additional backplane is 8-port
not 4 with some additional information on spreading them across channels.
Also kudos to Al, who had some excellent details related to performance
issues. The external hard drive was a bad idea (I was trying to get out
cheap). I will live with the hardware as it is.
My decision is to use SDS and mirror my partitions (if I have room) and not
use RAID 5, forget the external hard drive, purchase a larger hard drive
when it is time for growth. Plan also to petition for the additional
backplane. I usually don't get extra parts that are needed until something
goes wrong or performance is a real issue. That is when "they" notice and
by then the System Administrator looks bad. everyone.

Original Question-
New E450 with 4 -18GB HD's. No hardware RAID controller. Planning to do
software RAID 5 w/SDS. The only problem is that device 0 with my OS will
not be on the RAID 5 device. Instead of spending money on another 4-slot
UltraSCSI backplane for a single drive, can't I add an external hard drive
as a mirror to my OS on the external SCSI port? It will also need to hold
the DLT8000 on that same external port.
The reasoning being that if we implement a RAID 5 device it will be much
easier to grow (add another partition) down the road than mirror devices
for both OS and data (which will have to be reconfigured ) . The main
reason I am asking is that the Owner's Guide only mentions adding tape
devices off the external port.

Thanks for any insight.

April Sims MCSE, CNE Abilene Christian University
Systems Administrator ACU Box 29005
Information Technology Abilene, TX 79699 Vx:(915)674-2681 Fx:674-6724

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