dev => udev
Posted Feb 26, 2007 4:27 UTC (Mon) by bojan
In reply to: dev => udev
Parent article: ESR's goodbye note
> why you'd need to "clean out" /dev when moving to an udev-based system
Well, if you run "yum upgrade", it is a fact that that's is what's going to happen: upgrade to udev will remove dev, which will remove all entries in /dev.
As you explained, it is not necessarily what needs to happen - but it does by default. So, unless you're prepared for some creative surgery (as per you explanation), you will get screwed.
Coming back the original question of supported upgrades from CentOS 3 to 4 (or RHEL 3 to 4), it is obviuos why this is not a recommeded thing to do - people don't normally want to recommend a complicated and risky process that would in the end require a reboot anyway (new kernel). RHEL packages were designed to be upgraded using the upgrade process, not "yum upgrade" (remember: RHEL 3 and 4 don't even ship yum, it's a CentOS addition).
You can find some more info here (search for udev):
Note how you have to be on 2.6 kernel before starting this. CentOS 3 (i.e. RHEL 3) is based on 2.4 kernel.
Instead, one cuts a small kickstart file, starts an upgrade and after some minutes has a fully upgraded system with far less risk of stuffing things up.
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