Re: EMC DASD

Al Barsa, Jr. wrote:
>Most of my customers have RAID-5, no one has ever had a problem!   I don't
>think that mirroring is necessary unless you are 911, or a hospital, etc.
>I do have some mirroring customers still, but most have backed off to RAID-5.

I work at a hospital and we use RAID-5.  However, we have no
applications on the AS/400 530 which would directly affect patient
care if the system went down.  It would hurt the financial side of
things though!  That said, we did implement Vision Solutions' OMS Gold
Suite last year and are mirroring to an identical AS/400 530.  Should
our primary system fail we could be back up and running in 30 minutes.

As for disk mirroring, a while back when we only had one AS/400 F80
using mirroring, we had a system crash due to DASD failure.  A disk
crashed, and corruption was mirrored to the mirror disk.  We had the
highest level of mirroring available.  IBM was never able to explain
what went wrong or why the mirroring failed to do it's job.  We were
down for almost three days.  We upgraded the F80 to a 530 soon after,
then purchased a second 530 along with OMS, largely driven by our
memories of that week of hell.  Disc mirroring and RAID-5 are great,
but don't be lulled into a false sense of security.  If you truly need
high systems availability, a second AS/400 and mirroring software is
the only way to achieve it.

Terry Herrin
Sr. Programmer/Analyst
New Hanover Regional Medical Center
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