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Re: AW: AW: How to check integrity of database?

From: Paul Koning <pkoning_at_equallogic.com>
Date: 2005-10-05 17:12:38 CEST

>>>>> "Markus" == Markus Karg <markus.karg@quipsy.de> writes:

 Markus> I don't know the internal structures of FSFS, but what
 Markus> happens if FSFS returns buggy data? Is svn verify checking
 Markus> that the data is correct or does it trust on FSFS to never
 Markus> return buggy data (i. e. data that looks correct but actually
 Markus> is screwed: e. g. the original source line would be "class x"
 
 Markus> but FSFS returns
 
 Markus> "class y"
 
 Markus> because of internal mislinked pages.
 
 Markus> Can this happen in FSFS and if it happens, does svn verify
 Markus> detect it?

If that is the sort of thing you're worried about, the issue isn't
structural integrity, but data integrity. While it's possible for the
database to mess this up, the file system could also do it. And the
hardware is the most likely cause of problems -- CPU, bus, memory, I/O
channels, disk drives...

As Matt England pointed out, if this is what you're worried about, the
only answer is going to be to generate and save checksums (md5sum or
better) for every file. You can then regenerate them and check for
changes.

You may also want to examine your hardware for unprotected data
paths. Typical PCs contain quite a bunch of those; server-grade PCs
probably fewer but the number may be nonzero even so.

         paul

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Received on Wed Oct 5 17:14:53 2005

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