Now that FC6T1 is upon us, I''m wondering if it is supported to run an FC6Tx domU as a guest of an FC5 dom0 host? Or an FC5 domU as a guest of an FC6 dom0 host? If possible would this require synchronised xen versions for guest and host domains? I see using xen as a good way to make upgrades less painful by live migration of guests between hosts while the hosts are upgraded, and by splitting functions of a server into multiple guests which can be tested/upgraded individually. Allowing mixed domains could ease the "upgrade treadmill" of Fedora, and reduce the possibility of breaking everything at once during upgrades. Presumably RHEL5 customers will eventually ask the same questions about supporting mixed RHEL6 upgrades with xen? Getting this right would give xen/linux the "no downtime" functionality I recall from performing rolling upgrades across nodes in VMS clusters years ago. Thoughts?
On Sat, 2006-06-24 at 18:38 +0100, Andy Burns wrote:> Now that FC6T1 is upon us, I''m wondering if it is supported to run an > FC6Tx domU as a guest of an FC5 dom0 host? Or an FC5 domU as a guest of > an FC6 dom0 host? If possible would this require synchronised xen > versions for guest and host domains?In theory this should be possible but I''m still trying and not able to do fc6 (guest) on fc5. I''ve been told that fc5 (guest) on fc6 (actually just running an fc6 kernel) should work but I''ve had no success with that yet either. Mind you my requirement is a bit of a big ask I guess, in that I would only consider this to "work" if I can run the xenguest-install.py successfully. There is apparently an incompatibility in the kernel interface as fc6 has a later snapshot of xen. I expect things will improve soon.> > I see using xen as a good way to make upgrades less painful by live > migration of guests between hosts while the hosts are upgraded, and by > splitting functions of a server into multiple guests which can be > tested/upgraded individually. > > Allowing mixed domains could ease the "upgrade treadmill" of Fedora, and > reduce the possibility of breaking everything at once during upgrades. > > Presumably RHEL5 customers will eventually ask the same questions about > supporting mixed RHEL6 upgrades with xen? Getting this right would give > xen/linux the "no downtime" functionality I recall from performing > rolling upgrades across nodes in VMS clusters years ago.I expect questions like this will come in think and fast. Setting up virtual test and development environments for multiple OS releases is likely considered "bread and butter functionality" for a product like xen. Ian
Ian Kent wrote:> On Sat, 2006-06-24 at 18:38 +0100, Andy Burns wrote: >> Now that FC6T1 is upon us, I''m wondering if it is supported to run an >> FC6Tx domU as a guest of an FC5 dom0 host? Or an FC5 domU as a guest of >> an FC6 dom0 host? If possible would this require synchronised xen >> versions for guest and host domains? > > In theory this should be possible but I''m still trying and not able to > do fc6 (guest) on fc5. I''ve been told that fc5 (guest) on fc6 (actually > just running an fc6 kernel) should work but I''ve had no success with > that yet either. > > Mind you my requirement is a bit of a big ask I guess, in that I would > only consider this to "work" if I can run the xenguest-install.py > successfully. > > There is apparently an incompatibility in the kernel interface as fc6 > has a later snapshot of xen. > > I expect things will improve soon.I just installed a rawhide installation as a XEN guest today on a updated FC5 dom0 with xen-3.0.2-3.FC5 and kernel 2.6.17-1.2139_FC5xen0. But after installing and booting a couple of times I get this error message: Error: Device 0 (vif) could not be connected. Hotplug scripts not working. A boot clears the problem, so I guess it is some kind of resources that isn''t cleaned up, probably related to (virtual) interfaces. All guests are LVM-backed so it''s not loop devices that''s exhausted.