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Re: Yum, Proxy Cache Safety, Storage Backend

Warren Togami wrote:

Even a postman is going to have trouble when you randomize the addresses...

The real solution that you need is within MirrorManager. Perhaps today MirrorManager will not do what you need. Let us define the functionality that you do need:

"Users should be able to define their own site-local netblock and associate it with a preferred public mirror. That preferred public mirror will then *always* show up as the first mirror, followed by others in the region."

Anything that requires coordination among any or all of the proxy manager or fedora users that happen to be behind the proxy just isn't going to happen here and I'm having trouble imagining an organization where it would. Can yum make this happen automatically, or without intervention, can the mirrormanager list always return the same first choice when requested from the same address? If that already happens, then maybe things aren't as bad as I thought.

Want to help write this option into MirrorManager?  The code is open.

Tim "Proxies is nothing but trouble" :)

The yum developers have an erroneous assumption that only "broken" proxies are at fault for yum problems. I have described at the beginning of this thread that this assumption is false. *Any* proxy server that does caching will occasionally cause the partial sync yum failure, or resigned RPMS will cause a failure.

I'm missing something here. A cache is only going to resend what it got the first time. If the first user got the right thing, so will the second. If the first user got something wrong, don't blame the cache for it.

Fortunately, the yum developers were already thinking about using unique (probably SHA1) names of repodata as of yum-3.2.9 for other reasons. This should solve the common partial sync failure in Fedora 9+.

This should be needed to fix the first user's problem as much as subsequent ones.

Note that if yum acted intelligently with proxies, the whole concept of mirror management could be replaced by appropriately placed squid (or similar) proxies with no configuration/maintenance other than setting them to cache large files and restricting public ones to certain targets. Then if yum noticed that no local proxy was being used, it could use some mirrorlist-like mechanism to find one nearby and use it explicitly, eliminating any need for a reverse-proxy setup on the proxy server side.

I can't begin to respond to this because of how misguided it is.

I think anything that needs individual per-distro, per-version, per-location management just to act like a working cache is even more misguided, but maybe there some other approach that would work. Perhaps you could ask the squid expert if a slightly more intelligent client could eliminate that need and make cascaded proxies work better.

   Les Mikesell
    lesmikesell gmail com

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