Hal Merritt pisze:
Perhaps if you look only at the media proper, but perhaps not if you look at
the TCO*.
A tape based solution almost invariably includes many humans and physical activities in the process. That's expansive. Darned expensive. And slow. Very slow.
Bad assumptions. No human interventions are necessary. Have you seen
about ATL? Autmated Tape Library?
Worse, in a DR scenario physical tapes are S-L-O-W because they have to be transported via PTAM* from the storage site to the DR site. This can push a MTR* out to a couple of days.
Again, BAD ASSUMPTION. No need to PTAM. ATL can reside in DR datacentre.
The second one. Forgive me malice: how fast are non-tape media when
transported via PTAM? Are the disk any faster during transportation?
These days, one can link a couple of DS8100's and have critical data redundancy for a very competitive TCO. Depending on your specific situation, you could set a realistic MTR objective of an hour or so.
Don't confuse backup and replication. Even three-site solution does not
protect you form human or application error. Mistakenly deleted dataset
is deleted in both primary and secondary site. PiT copy is the solution
but quite expensive for medium and large amounts of data.
> *TCO = Total Cost of Ownership. The total bottom line dollars
> involved.
> *PTAM = Pickup Truck Access Method. Physically moving a tape cartridge
> from site A to site B. (From an IBM Redbook on the subject.)
> *MTR = Mean Time to Recovery. The total clock time from the point
> where normal processing ends to the point where normal processing
> resumes as if nothing happened.
MTR usually means time to REPAIR. Your descriptions regards RTO -
Recovery Time Objective (Recovery Point Objective, Recovery Time
Objective - crucial parameters for any DR and backup plans). Of course
this is acronym, and by definition can be overloaded (have different
meanings). I presented popular ones in this context.
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