Re[2]: [rdiff-backup-users] Verify times increasing

[listserv . traffic]

I know Matt corrected this post, but I wanted to address this:

---
If you do a --verify-at-time xyz where xyz is your oldest backup, it
should verify all files in that backup - so every delta should be
applied. This should verify that all delta's (backups) are good and
functioning.

[In short, it "verifies" that for each file for which a successful
verify is returned, that the most current file, all applicable delta's and 
meta-data
are good and functioning properly.]

---
However, if files were added after the initial backup, I'd guess that
a verify won't check the delta's for those files - since they don't
exist in the set at time xyz

So, while a verify to your oldest backup is good, it's not
comprehensive for all files that have deltas+meta-data.

---
I'm not aware, so if I'm wrong perhaps someone could correct me, but
I'd like a command to, in essence, do a comprehensive
--verify-all-files-in-the-archive. [I'm pretty sure such a thing
doesn't exist, at least I never saw it in the docs.]

This would apply all deltas to *all* files (back to the oldest copy) and 
compare the stored
hashes at the time of backup to the rebuilt file. [Note all the
files, not just those in a particular target date/delta.]

This wouldn't verify that every file would be correct in every delta
version, but it would, I think, get as close as one might come to
that.

Then again, doing an intermediate check of the hash and file at each
delta point wouldn't take too much longer [or so I think without a
lot of time invested in pondering it] - so if this option/feature doesn't
exist and one were to code it, it might not be much more code or
difficulty...

Thoughts?

-Greg



> 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