Summary of "RAID disk systems?" inquiry

From: Joe Garbarino (
Date: Fri Apr 26 1991 - 16:01:40 CDT

On the 15th, to make a decision between SCSI, IPI, and RAID disk
subsystems, I asked the questions

>Has anyone had experience with RAID disk arrays? How about software
>striping, does it put too much of a burden on the CPU? Any
>experiences good or bad would be appreciated.

Since then I have received information from Ciprico on their new RAID
system, which connects 5 ESDI disks to a controller that then connects
to a 32-bit SCSI controller card in a Sun VME chassis. You end up
with about 2GB of data (if you start with 1.2GB disks). This includes
the ability to "hot swap" one of the disks, since one of the disks is
used as a parity disk. The name Storage Concepts was also brought up,
but I didn't contact them.

One person responded that there have been studies that suggest that a
string of SCSI-2 disks can outperform IPI disks when the system is a
server that is doing random reads on multiple disk, and is
significantly less expensive.

There was some question about whether RAID systems providing a
performance boost when reads are done in a random fashion. Rotational
latency seems to loom as the largest bottleneck. Possibly the
increased RPMs of some of the newer drives (Seagate Elite, 5400 RPM)
will help this.

We purchased a combination of IPI and SCSI disks.

No one responded with actual experiences with RAID systems or software
disk striping, I guess that's to be expected with fairly new
technologies. Thanks to those that did respond (you know who you

Joe Garbarino -- ERIM

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