John S. Giltner, Jr. wrote:
Chantal wrote:
That was my argument as well. How to do offsite backups. My classmate
mentioned the possibility of a remote SAN for companies that already
have the infrastructure and bandwidth available to them. I'm really
not sure how feasible that is though.
It is totally feasible. There are companies that have remote DASD/SAN's
and they really don't do backups, they do PPRC or XRC.
That's the most serious mistake they can do!
"Regular" Backup is *not* for DR. What will they do when you delete by
mistake some datasets ? The "deletion" will be synchronously replicated
to the other site.
"Offsite" backup is different animal. However it is worth to consider
whether you will need backup (and *migration*) tapes in DR site.
Guess where the remote DASD/SAN are located? At their DR site. The DR
test involves "breaking" the copy connection, IPL'ing off the DASD/SAN
at DR and they are up and running. I heard that on site that does this
for one of their DR tests they were up and fully running in about 15-30
minutes.
...and they have no DR solution during the tests and after that, until
the DASD will get mirrored again. It can be matter of days.
Typical approach, unfortunately.
Solution: tertiary storage. You can do Snapshot/FlashCopy/WhatEver from
secondary to tertiary and do your tests.
BTW: 15-30 minutes is another myth. It is time for IPL. Where is the
time for check-out procedures, where is time for crew arrival (I assume,
they're not waiting for disaster), where is the margin for emotions (to
calm down).
What some sites do is backup to DASD locally to reduce
system/application outage time and then backup the DASD backup to tape
and send the tape offsite. Currently we have a two hour hard window
where all of our applications must be out of service. We are going to
start doing the DASD to DASD and then to TAPE thing and hopefully get
down to just a few minutes.
Depending on application design it may be unnecessary to make any backup
window. We're open 24x7 and have backups.
DASD mirror (FlashCopy, Snapshot) can reduce backup window, regardless
of the backup media (disk or tape).
Regards
--
Radoslaw Skorupka
Lodz, Poland
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