Yum: the dreaded metadata disease

[Michael Schwendt]

On 18/12/2007, Timothy Murphy wrote:
>
> My laptop seems to have contracted the yum disease:
>
> [Errno -1] Metadata file does not match checksum
>
> I googled for this, and it is apparent that this is
> a world-wide disease.
>
> IMHO, this error message is VERY BAD.
> It may make the yum developer happy,
> but it is completely useless to the yum user.

Yes, it's a pain. I agree wholeheartedly. With a bit luck you can
continue after a " yum clean metadata". But the cure cannot be
guaranteed.

It's a too simple implementation of repository metadata caching which
breaks in conjunction with the fedora mirroring system. What happens
is that Yum downloads a repository metadata index file (repomd.xml)
from the first mirror server on the list of mirrors, stores it below
/var/cache/yum/<repository-name-here> and then tries to download the
larger [compressed] metadata files while paying attention to the
checksums listed within the saved repomd.xml file. If the connection
is interrupted somehow and another mirror is contacted, that mirror
may offers files with a different age which don't match the initially
downloaded repomd.xml. Instead of starting with a fresh download of
all relevant files, Yum insists on keeping the cached repomd.xml
(until its expires in accordance with the value in /etc/yum.conf),
although it is only ~2KiB short.