[Discuss] Backing up LVM partitions using snapshots

[richard.pieri at gmail.com (Richard Pieri)]

On 12/19/2011 12:34 PM, Derek Martin wrote:
> They do require constant power: human power.  You didn't account for
> paying the labor to jockey all that tape around and do back-up
> verifications.

Actually, I did.  Manhandling is included in Iron Mountain's rates, as 
is tape and carton indexing.  YMMV with other records storage services. 
  Validation is done automatically by the backup system.  Yes, this can 
be automated with tape, too.

> And nothing is infinite... Your back-ups will eventually take long
> enough that you need to buy additional tape hardware to get them done
> in the required time frame.

This does not follow.  If I have 300TB of available storage then I will 
need 300TB of backup capacity that can do full dumps within my full dump 
window.  I'm going to acquire that before the 300TB storage goes into 
production.  Of course, I won't need 300TB worth of tape loaded at the 
outset.  Just as one can expand an unpopulated storage server by adding 
more disk to the disk cage, one can expand an unpopulated tape changer 
by adding more tapes to the changer trays.

Full dumps will always be completed within the required time frame. 
That's a requirement of the tape library.  Incremental dumps will always 
be smaller than full dumps and will always be completed in less time.  I 
only need to buy more tape hardware when my available storage expands 
beyond my backup capacity.

> Note that up to a point, some shops can make the incremental labor
> cost of tape *seem* negligible too, by forcing their existing IT staff
> to work more overtime.  This eventually will result in higher salaries
> or higher turnover, so the cost is still there, but it's hidden and
> harder to account.

There are only two kinds of occasions where I've worked "overtime" (I'm 
exempt) with tape-based backups.  The first is disaster recovery 
situations where I'd be putting in the time regardless of backup system. 
  The second is at my current gig where I need to be on site to do the 
annual top-level dump for my AFS cell.  That's only about 3-4 hours on 
New Year's Day, baby-sitting rather than doing real work.  I'm comped a 
full day for the time so I'm actually putting *less* time in for that 
week than normal.

-- 
Rich P.