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Re: Lack of Subversion repository recovery tools

From: Erik Huelsmann <ehuels_at_gmail.com>
Date: 2007-06-29 16:18:51 CEST

On 6/29/07, david.x.grierson@jpmorgan.com <david.x.grierson@jpmorgan.com> wrote:
> The problem is that hardware faults and errors don't just occur on the
> server side where you have significant control over them - they can often
> occur on the client as well.
>
> I experienced a situation where a repository of another SCM tool was
> corrupted because the client network driver was erroneously inserting
> nulls into files while they were being transferred across the network.
>
> We were initially unaware of the issues because the SCM solution was
> (correctly) recording the contents of the files which were being presented
> to it as the new revision and developers were going on continuing their
> development.
>
> Eventually (a week or so later) they were unable to modify the objects
> which had become corrupted. Fortunately the SCM system had tools for going
> through the repository identifying the components which were corrupted and
> then recovering their contents appropriately.

Subversion protects you of problems like these: it sends over a delta
and the md5 of the resulting fulltext if you apply the delta to the
base-fulltext. Any additional or replaced bytes would result in md5
checksum errors.

> If you're in a job where you're able to turn around to management and say
> "sorry we've lost the last week's worth of development & it'll all just
> have to be done again because our SCM system doesn't let us fix things"
> then you're in a position of real power.

How would you want the SCM tool to address an issue like this?

(I'm quite serious here: how would your SCM tool know the NUL
characters don't belong there, more importantly, how would it know
which characters DO belong there?)

I do sympathise with the problems raised, but I'm not understanding
what it is that you're asking for: Subversion WILL let you fix it as
long as you know which characters should be there, you can always
check out the wrong data and commit the correct data (which comes as
close to 'repairing' the data as I can imagine...)

bye,

Erik.

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Received on Fri Jun 29 16:19:07 2007

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