Consistency checks / svnadmin dump/verify

[Felix Natter]

Dear subversion community,

as part of a daily backup process, I do "svnadmin dump"s, gzip them
and create several encrypted backups of the "*.dump.gz".

Now, the svn admin dump step (svnadmin dump -q ...)
worked without errors (exit code 0 and no errors on stdout/stderr),
and during the next step (encrypted backup) the VM crashed.

When looking into the log, I see that there was an I/O error on the
disk which is used by the VM. Now I now that the foo.dump.gz
are correctly backed up, but are they consistent (i.e. not affected
by the I/O error(s))?

So the question is: Does "svnadmin dump" do some consistency
checks (like svnadmin verify does)?
Regarding "svnadmin verify path/on/server": Can I be sure that
this does not modify the data?

Or do I have to use "svnadmin load" (on another machine),
does "load" do more consistency checks?

Many Thanks(!) and Best Regards,

Felix

--

SIDACT GmbH
Simulation Data Analysis and
Compression Technologies

Felix Natter
Software Developer

Auguststraße 29
53229 Bonn
Germany

Phone	:   +49 228 5348 0430
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Email	:   felix....@sidact.com
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[Andreas Stieger]

On 2023-09-28 17:28, Felix Natter wrote:
> So the question is: Does "svnadmin dump" do some consistency checks
> (like svnadmin verify does)?

Probably not. Specifically it does not *test* that the dump can be
loaded. Although that would certainly be a bug. I actually do not think
that this is the best way of thinking about this. Maybe you should be
thinking about "backup verification" instead? Start from the backup
result (the compressed data), and regularly ensure it can be loaded and
verified.

> Regarding "svnadmin verify path/on/server": Can I be sure that
> this does not modify the data?
>

It is read-only.

> Or do I have to use "svnadmin load" (on another machine),
> does "load" do more consistency checks?
>

I do recommend to use "svnadmin load" as a signal that the backup can
actually be restored.

Andreas

[Felix Natter]

hello Andreas,

many thanks for the quick answer. I found this link:

https://svnbook.red-bean.com/en/1.7/svn.ref.svnadmin.c.verify.html

which states "... This basically iterates through all revisions in the repository by internally dumping all revisions and discarding the output—...".

which leads me to think that "svnadmin dump" does the same checks as "svnadmin verify".

Anyway, I do get your point that it is a good idea to "load" the repos every month
or so.

Many Thanks and Best Regards,

Felix