[Fedora-xen] Possible Stupid Question...

[Dustin Henning]

David,

                This is probably a "something stupid" related to Linux more
than Xen.  It sounds like the system isn't booting at all, and the most
likely cause is that the drivers necessary for the SAS are not in the
kernel.  Linux picks appropriate drivers for the machine you install on and
then all updates use those drivers, so when you move to new hardware, it
just doesn't work.  If you copy the kernel and modules from the working
machine to the machine that didn't work when you did your dd_rescue, it
might boot with them, however, when it comes time to update, you will need
to manually compile your new kernels instead of using the standard automated
update method, i.e. do the standard update, ut then do a custom compile and
boot to the custom kernel, not the one from the standard update, as it ill
crash, but the custom compiled one will be compatible with the other changes
made by the automatic update.  This is far from detailed and complete, as it
has been a while since I have dealt with that kind of thing, but I most
often experienced it switching from "Compatibility Mode" SATA to AHCI on
some machines that I didn't want to rebuild.  I n your case, a rebuild on
the problem machine is probably a better option, as you can then migrate
whatever you want however you want to a clean machine with no thorn in its
side.

                Dustin

 

From: fedora-xen-bounces at redhat.com [mailto:fedora-xen-bounces at redhat.com]
On Behalf Of David Levinger
Sent: Tuesday, April 01, 2008 20:57
To: fedora-xen at redhat.com
Subject: [Fedora-xen] Possible Stupid Question...

 

Hey guys,

Been loving Xen and playing around with it for awhile now but recently tried
something new and had a really weird result, not sure if it is at all
related to Xen so I'm gonna ask here.

1. I have a SATA based Xen x64 machine running a para-virtualized x64 VM,
that VM is written out to an LVM Partition. /dev/vgmachine/lvVM
2. I shut down that VM and then dd_rescue it over to another machine. (With
the same LVM setup)
3. The other machine is running the same exact host OS but has SAS based IO
instead of SATA.
4. When I bring up the Xen machine on the SAS host the whole computer gets
hosed. I see SAS controller errors and I have to hard power the machine.

I'm building a new Xen machine on the SAS host now and it doesn't seem to be
causing trouble, did I do something stupid in assuming that I could move a
Para-virtualized machine from one type of IO to another?

David

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