Hi,
Jeffrey J. Kosowsky wrote on 2011-07-03 20:29:48 -0400 [Re: [BackupPC-users]
Recompressing individual files in pool]:
> Holger Parplies wrote at about 20:10:20 +0200 on Sunday, July 3, 2011:
> > Kelly Sauke wrote on 2011-07-01 09:21:28 -0500 [[BackupPC-users]
> Recompressing individual files in pool]:
> > * Does your update change the partial file md5sum? If so, you'll need to
> > move the pool file to its new name and location. [...]
>
> Yes - unless you are just changing content between the first and last
> chunks (keeping the file size the same), the partial file md5sum will
> change.
not quite exact ;-), but close enough for this thread.
> That being said, while it is technically correct and advisable to
> rename the file with the correct partial file md5sum (including
> adjusting the suffix for potential collisions), it is not strictly
> necessary.
True, of course. You don't even really need the pool file. Actually, I'd
consider *removing* the pool file rather than leaving it in the pool with
an incorrect name (of course that includes adjusting collision chains).
Incorrectly named pool files just add work for BackupPC when trying to
match new content to existing pool files. Am I missing any side effects
and end cases? Statistics will be inacurate?
> Another perhaps more important issue is that you really need to change
> the attrib file.
And here, again, you need to note that attrib files are also pooled, so you
can't simply change the attrib file in place.
Note that this also rules out simply modifying the pool file - you need all
the pc/ files linking to it, because you need to modify all their attrib files
(presuming you *are* changing the file size). But I somehow have the
impression you weren't going to do that anyway.
> The bottom line is that editing existing files is possible (and indeed
> I do a lot more 'messy' things in my BackupPC_deleteFile routine)
> *but* you need to think of all the side-effects and end cases to make
> sure you won't be messing anything else up.
And as you see, it can get quite complicated. We haven't even touched on
the matter of backup dependencies yet. Supposing you only want to change a
file for a specific (range of) backup(s), you may need to add the file with
its previous contents to the next backup after the one(s) you want to change.
Well, any of that may or may not apply to what you actually want to do. Could
you perhaps be a bit more specific?
Regards,
Holger
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