Re: [rdiff-backup-users] Verify times increasing

[Matthew Flaschen]

Daniel Miller wrote:
>> I think you are misunderstanding how --verify works.  If you say:
>>
>> rdiff-backup --verify-at-time 1Y
>>
>> it does not verify the last 1 years worth of backups.  It verifies a
>> single backup a year ago (I believe the closest backup before that exact
>> time); hence the name "verify-at-time".
> 
> Yes, I do understand that. But to verify a one-year-old backup it must
> apply each set of differential data over that entire year to reconstruct
> the files as they existed one year ago.

That is incorrect.  "Every 10 incremental diffs, rdiff-backup stores
another snapshot of the file. [...] During the restore, rdiff-backup
finds the oldest snapshot at least as recent as the desired backup time
(it could be the current mirror, or one of these snapshots)."
(http://www.mail-archive.com/address@hidden/msg03884.html).

> I'll address your second assertion first: I'm getting less verification
> than I thought. I maintain that it is effectively verifying the
> integrity of every backup increment between now and the point in time
> that I verify since it uses each of those increments to construct the
> point in time that I'm verifying. Please explain how my understanding is
> wrong.

This follows from what I noted above.  To do a verify at 1Y ago, it will
 (on average) only process 5 rdiffs.  It may process 10 or 0, but that's
the average.  You are only verifying the backups immediately after the
1Y ago mark.

Matthew Flaschen