We are considering switching from Jamaica to Nike for the following reasons:
*       Software mirroring overhead with Jamaica has negatively affected
system performance.  We have a write intensive environment.  HP has looked
at it and agreed that in a write intensive environment, Mirror/IX may cause
more CPU and Disk overhead than the 2-3% documented.  It has required
significant disk management to keep the system performance acceptable.  We
moved all user files off the master disks on to other disks and built huge
empty files on the masters as placeholders to prevent new files from being
written to them.
*       Nike can mirror system volume set.
*       The system is vulnerable to disk failure when the mirrors are
re-syncing after an incomplete reboot or anything else that can cause a
mirrored set to become disabled.  (Murphy's law - We lost a disk during a
resync and it was disastrous.)  We've changed our environment to eliminate
frequent reboots.  No one mentioned the mirror would have to re-sync every
time you reboot and don't get to a shut (6).  (We had a problem with hung
sessions that we have since resolved.)
*       Since August HP has replaced six 9 gig Jamaica drives that have
become disabled and refused to re-enable.
*       Nike has the option to have a redundant processor.

The cost for Nike is significantly higher than Jamaica, but I know if we had
it to do all over again we would definitely go with Nike in the beginning.

Kara Strunk
Data Systems Manager
[log in to unmask] <mailto:[log in to unmask]>
Maritz Marketing Research

                -----Original Message-----
                From:   bill grefe [mailto:[log in to unmask]]
                Sent:   Wednesday, February 03, 1999 10:44 AM
                To:     [log in to unmask]
                Subject:        Disks!, Raid? Mirroring?

                After yesterday's long ordeal with a flaky (technical term)
2gb disc drive
                (ldev 1 no less) I would
                like to know this learned group's opinion on how best to
insure against data
                loss (and down time)
                for the loss of a disc drive.  (Friday's backup failed to
verify 28,000
                files and the drive failed during
                the Monday night backup. Murphy was at work.)

                Raid? Mirroring? Jamaica? Nike? What are they?

                What are the pros and cons?

                My environment is a 957RX with 8 - 2 gb drives (C2490) in
one (long volume
                name) volume
                20 or so image users and 40 resource sharing users.

                Least cost and simplicity would be the operative design
goals.

                My thanks to the HP CE for trying ALL the options to recover
the data (which
                luckily he did) and
                Pete Crosby at the response center for the quick, accurate
and thorough look
                of the dump.

                William Grefe
                [log in to unmask]
                PCI-WEDECO Environmental Technologies, Inc.
                phone: 973-575-7052
                fax: 973-575-8941

                "When a man sits with a pretty girl for an hour, it seems
like a minute,"
                explained Albert Einstein.  "But let him sit on a hot stove
for a minute,
                and it's longer than any hour. That's relativity."