RE: EMC DASD vs. IBM DASD and MIMIX for 24/7 operation

["Jones, John \(US\)" <John.Jones@xxxxxxxxxx>]

I haven't responded before since we only use internal DASD on our
iSeries machines.

First, get to V5R3 if you aren't already there.  Unless you've an
application compatability issue, there is no good reason to not make the
move.

Second, I would recommend finding the quietest time period (least
activity) and doing a save-while-active (SWA) during that time.  The
checkpointing won't take that long (probably 10-20 minutes), especially
if you checkpoint your production data libraries in one group and your
other databases/*USER libs in another.  Once the checkpointing is done
you don't really need to care about how long the backups take to spool
to tape.

Third, for the reorgs, under V5R3 you can reorg in the background
without the need for an exclusive lock on the physical file.  No more
downtime window requirement.

I haven't played with the reorgs yet; haven't had a need.  But for
backups we do a SWA of our production databases nightly without bringing
down the app servers.  Each database's group of libs is saved
sequentially so there are multiple (but smaller) checkpoints.  For the
non-database stuff & IFS stuff, we do a SAVCHGOBJ and specify
UPDHST(*NO).  We also do a SAVSECDTA and SAVCFG nightly.  Periodically
(weekly, but with the new year it'll move to monthly) we do a GO SAVE/21
(actually the BRMS equivalent) and IPL.  The 21 save does update
history.

Net result: To restore in a DR situation, we restore the latest monthly
followed by the latest daily.  To minimize that restore time, we will be
moving to always restore the monthlies on our DR box, so a real recovery
will actually be limited to just the latest daily.  And we're
continually testing our recovery capabilities.

Assuming you're under software maintenance, the above can be done for
free (+ labor).  If you've some money to spend, consider LTO3 tape
drives (assuming tape may be a bottleneck).  What hardware & OS are you
on?

Also, in a future release (not sure if R4) we will be able to do virtual
tape - do your SAVLIBs, SAVSYS, etc. to virtual tape volumes (like the
virtual optical support we have now).  So the above can apply to
disk-to-disk-to-tape backups.