I'm deploying a NetApp Virtual Tape Library at work right now, and I
have an engineer from NetApp coming in to help me set it up. I was
explaining to him how we rotate tapes, and he seemed a little
bewildered at our rotation method. I've never done tape
backup/recovery anywhere else, so to me, our way is "normal", in that
it's the only way I've ever been shown how to do this.
- - = = Cycle = = - -
About 99% of our customers are backed up via policies with the
* They get a Full backup 1 night a week and differential-incrementals
the other 6 nights.
* We have an on-site vault where tapes go for a week. After a week,
Iron Mountain comes and gets them.
* We ship Full AND Differential-Incrementals off-site for 90 days
(<--- This is the bullet point that bewilders my VTL engineer)
In laying out the VTL, my NetApp engineer tells me that he wants to
make a virtual library for all Full backups and a Virtual Library for
the Diffs. I figured we'd just have 1 virtual library for everything.
He explained to me that since we want to write the Full backups out to
physical tape, that we need a separate Virtual Library for the Full
backups on so that we can enable the "Direct Tape Creation" feature on
that VTL. When I told him I needed to write the Diffs to physical tape
also, so that I could send both offsite, he seemed to think that was
really odd. He claims that all the other VTLs he's deployed typically
look like this:
* Fulls are written to VTL, then to tape (D2D2T). The physical tapes
are then sent offsite for whatever the retention period is.
* Differential-Incremental and Cumulative-Incrementals are written to
the VTL, but then they sit there for maybe 2-4 weeks. They are never
written to tape, and therefore never sent offsite.
On one hand, I kinda understand the logic here. If the definition of
Differential-Incremental and Cumulative-Incrementals is essentially
differing levels of backups since the last full, it wouldn't make
sense to write incrementals out to tape since next week's Full starts
the process over again.
However, in the SLA I have with my customers, I state that I can
recover data from any point within a 90 day window. While the chance
is slim, there's always that possibility that I get a restore request
to recover a file from 89 days ago. If I'm only sending full backups
off site, I'd be able to recover the full backup, but I wouldn't have
any incrementals to restore that file to the exact point in time my
So, I guess my question is:
How does everyone else handle incrementals? Do you send them offsite
with the Fulls, or do you just have Fulls go offsite and keep
incrementals onsite for X retention period?
- Heathe Kyle Yeakley
Veritas-bu maillist - Veritas-bu AT mailman.eng.auburn DOT edu