Re: Bug#531154: mirrors: Same problem on ftp.uni-kl.de
Simon Paillard (simon.paillard@resel.enst-bretagne.fr) wrote on 14 June 2009 17:37:
>reopen 531154
>retitle 531154 libasound2_1.0.20-2_amd64.deb corrupted on ftp.de.d.o and consequences
>thanks
>
>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
> files
>* 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:
Yes. Mirrors, at least the primary ones, should verify the checksums
from time to time. We do it at least twice a year.
>wget -q -O - http://some.mirror/debian/indices/md5sums.gz | gunzip -c - | LANG=C md5sum -c - 2>&1 | grep "FAILED$"
A mirror should already have it, wget is not necessary.
This will take a looong time... One might want to run several md5sums
in parallel. It'll be much faster but will put a heavy read load on
the disks.
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