Re[4]: [rdiff-backup-users] Verify times increasing

[listserv . traffic]

I mis-posted, and should have replied to the list, instead of just
Daniel...so here it is...

---
I'm not sure what you're doing with your --verify... [I'm confused, I
think...]

It *sounds* like you want a full CRC style check of the *current*
files after the backup is complete. (i.e. File X gets updated today with a
delta, and you want to verify that file X is the same both on the
source and destination locations/drives after the "backup" is complete.)

If that's the case, I think you already get it. (It's "built-in" to
RDiff-backup.)

Before I type a lot of drivel, let me know if that's what you
want/intend.

--
If I understand you right, this is a very different animal than a --verify...



-Greg

> Greg wrote:
>> 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.]

> This is what I thought. It is good to have it confirmed. Thanks.

>> ---
>> 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.

> This seems to be a weakness in the rdiff-backup verify mechanism. I  
> think there is general consensus here on the list that this could be  
> improved since what many people are looking for is a way to verify  
> that their backup archive (including all past revisions) is free from
> corruption.

>> ---
>> 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.

> I agree, something like this would be great. Although with the speed  
> issue's I'm having it may not be practical (i.e. time feasible) to  
> reconstruct every file this way before comparing it to a signature  
> hash. I would propose that rdiff-backup store some additional meta- 
> data which would consist of signature hashes of the delta files as  
> they exist on the disk after rdiff-backup is finished with a backup  
> (similar to what yafic does - http://www.saddi.com/software/yafic/).  
> This should make the verification process much faster (yafic takes  
> less than two hours to verify an rdiff-backup repo that takes over  
> eight hours to --verify-at-time on my setup). Note that it would not  
> replace the --verify-at-time functionality, which would still be  
> necessary to verify the integrity of files as they existed before the
> backup. But it would provide a fast way to verify the integrity of an
> rdiff-backup repository.

>> 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...

> Ease of implementation may be an argument that favors your proposal.  
> My proposal adds a completely new layer of integrity checking on top  
> of the existing rdiff-backup functionality.

> ~ Daniel



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