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Re: Bug#531154: mirrors: Same problem on ftp.uni-kl.de

reopen 531154
retitle 531154 libasound2_1.0.20-2_amd64.deb corrupted on ftp.de.d.o and consequences

On Sun, Jun 14, 2009 at 12:10:14PM +0200, Adrian Knoth wrote:
> Package: mirrors
> Followup-For: Bug #531154
> I don't know if I should open a new bug, but I see the same problem on 
> ftp.uni-kl.de:
> [..]
> Failed to fetch  http://ftp.uni-kl.de/debian/pool/main/a/alsa-lib/libasound2-dev_1.0.20-2_amd64.deb  
> Hash Sum mismatch

A short status:
* rsync by default uses only modification time and file size to sync
* ftpsync doesn't use rsync checksum by default
* ftp.de.d.o (on top of many servers I guess) doesn't allow server
  checksum because of the impact on system load.

So as a consequence, if a file is corrupted (but mtime and size match)
on a rsync server somewhere between ftp-master.debian.org and a debian
mirror, fixing one primary rsync mirror is not enough.

The only ways to fix it are:
1/ on a rsync server with the fixed file: touch the modification time to
   force resync on downstream mirrors
2/ on every downstream mirror with bad file: touch the modification time
3/ on every downstream mirror with bad file: delete the file

Solution 2/ or 3/ can be automated by checking the MD5 sums of the whole
archive on a periodic basis, then delete them:

wget -q -O - http://some.mirror/debian/indices/md5sums.gz | gunzip -c - | LANG=C md5sum -c - 2>&1 | grep "FAILED$"

Remarks ?

Simon Paillard

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