Hello
Seems to me that the general consensus is to do schedules of daily
differentials, weekly cummulatives and monthly full backups with retention
periods such that the differential expires before the cummulatives and the
cummulatives before the full backups. How about the following ideas?
Establishing a baseline full copy with infinite retention. Duplicating the
baseline. Running daily differentials and weekly cummulatives with retention
periods where the differentials expire before the cummulatives. Whenever major
application upgrades or other work has been done, a new baseline can be cut and
the old one expired. Standalone drives local to the site can be used for the
baseline copies thereby allowing remote over the WAN operation where bandwidth
is limited. (Hey, I was asked to try and back up London from here and it would
take 28.5 days for a full backup so I need some optimization strategies).
Since in another thread, it has been alluded that incrementals are only versus
backups in the same class as the incrementals. If this is the case, two
classes could be established where instead of daily differentials, differentials
are every two days, alternating between the classes. The two classes could go
to different pools or even volume groups thereby protecting against single media
loss since the differentials are still being run each day but are versus not the
previous run in another class but the one prior in the same class and hence each
file revision is likely to get backed to two different volume pool/group hence
separate tapes within two days. Could make for automatic offsite policy if the
two volume groups are geographically separate but well linked (Hey, I've got
four computer centers in this city alone and two are connected by gigabit).
Can anyone confirm if incrementals are class specific (obviously I'll set up an
experiment but if someone knows, all the better).
Regards,
John I Wang
Sr. Systems Engineer
Steverson Information Professionals
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Enron Broadband Services
3 Allen Center 3AC872e
ph (713) 345-6863
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