> On Thu, 22 May 2008 10:26:32 -0700 Matthias Saou wrote: > > > I assume this is again due to the Xen version rebase, same as with > > the 5.0 to 5.1 update : After updating a Xen server (dom0) to RHEL > > 5.2 without rebooting on the newer kernel, some Xen related > > operations start to fail. > > > > Currently, I'm unable to start any guests (domU), and the behavior > > is not really helpful : "xm create -c foo" just hangs for a while > > and exits with the error : > > > > Error: Device 0 (vif) could not be connected. Hotplug scripts not > > working. > > > > ... > > > > This is quite annoying, as it causes problems which might go > > undetected for months (years?) and will bite at the worst possible > > moment : When a guest crashes and needs to be restarted... > > > > I wouldd really like to see some improvements to Xen is backwards > > compatibility regarding the kernel/userspace duo in dom0, as to > > "fix" this issue, if a reboot isn't possible (as other critical > > domUs might be running), a simple downgrade of the userspace xen > > tools might do the trick. So how hard would it be for the new tools > > to have the old behaviour if the old kernel is found? > > Just a head's up to the unwary, this is also(still) the case for 5.2 > to 5.3. I just had a domU go down on a box that got updated to 5.3 > and had to reboot the whole box to get things back up. Of course, > this required unplanned outages on other domU's that happened to be > on the same box. > > Now I know to only take the xen updates manually, when I can schedule > it.
FWIW, I've learned a few tricks to get things working again. Here are the most common : * After updating to 5.3, most of the "xm" commands don't work anymore. The solution is to downgrade xen and xen-libs for as long as the older kernel is still running. * If you can no longer start domUs, the creation seems to time out, it might be that udevd isn't running anymore. Just run "udevd &" and try again (I've seen this on *many* servers, not sure why udevd dies in the first place, though). * The network in a new domU doesn't work. You need to entirely re-create the Xen bridge interface from within dom0. I made myself an ugly script which removes members, deletes the bridge, creates it again and re-adds all of the same interfaces to it. I think my initial rant was actually the second one (udevd problem), now that I just read it again. HTH :-) Matthias _______________________________________________ rhelv5-list mailing list [email protected] https://www.redhat.com/mailman/listinfo/rhelv5-list
