I use a xen box to do test restores of customer backups to validate that the backed up data is actually enough to rebuild their servers from. This works really really well for restoring one or more physical machines and a workstation or two. We now have a few customers actually using xen on their own networks, so I am now faced with a new problem of how best to restore them... Being able to run Xen on top of Xen would solve that... is there a way? Or any other suggestions? Thanks James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
James Harper wrote:>I use a xen box to do test restores of customer backups to validate that >the backed up data is actually enough to rebuild their servers from. >This works really really well for restoring one or more physical >machines and a workstation or two. > >We now have a few customers actually using xen on their own networks, so >I am now faced with a new problem of how best to restore them... > >Being able to run Xen on top of Xen would solve that... is there a way?No>Or any other suggestions?You''ll need a dedicated box for recovery testing - recover their Xen Dom-0, then recover their DomU. -- Simon Hobson Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed author Gladys Hobson. Novels - poetry - short stories - ideal as Christmas stocking fillers. Some available as e-books. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
James Harper wrote:>I use a xen box to do test restores of customer backups to validate that >the backed up data is actually enough to rebuild their servers from. >This works really really well for restoring one or more physical >machines and a workstation or two. > >We now have a few customers actually using xen on their own networks, so >I am now faced with a new problem of how best to restore them... > >Being able to run Xen on top of Xen would solve that... is there a way?You can certainly slap xen into a linux (HVM) domain, installing dom0 as you normally might for your chosen distribution. This is the only possibility for ''nested'' xen-on-xen virtualization. Caveats: It is usually god-awful slow, partly mitigated via PV drivers in the ''child'' dom0. You are limited to running paravirt domUs within this child. I would not suggest such a configuration for anything other than experimentation/development. -s _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
James Harper ha scritto:> I use a xen box to do test restores of customer backups to validate that > the backed up data is actually enough to rebuild their servers from. > This works really really well for restoring one or more physical > machines and a workstation or two. > > We now have a few customers actually using xen on their own networks, so > I am now faced with a new problem of how best to restore them... > > Being able to run Xen on top of Xen would solve that... is there a way? > Or any other suggestions? >An hypervisor is able to run in a virtual machine if hypervisor construction and copmuter architecture meet the second Popek''s and Goldberg''s theorem (about recursive virtualization). Xen does not meet it, because x86 architecture is not a "perfect" virtualizable one. http://valent-blog.eu Chiacchiera con i tuoi amici in tempo reale! http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Mon, Mar 2, 2009 at 9:23 AM, Heli <helicoterus-elih@yahoo.it> wrote:> An hypervisor is able to run in a virtual machine if hypervisor construction > and copmuter architecture meet the second Popek''s and Goldberg''s theorem > (about recursive virtualization). > Xen does not meet it, because x86 architecture is not a "perfect" > virtualizable one.As has been said... yes you can. It''s not pretty, and certainly not recommended. I''ve done it before using RHEL 5 and Xen running an additional RHEL 5 HVM guest with Xen in that. It''s certainly ugly, and incredibly slow, but you can at least log in and use it. Now, that being said, would I try that "in the real world": absolutely not. Would I use that in your case of testing customer backups: No way... Sure it works, but it doesn''t work well, and I would not trust that to verify a customer scenario. Best bet would be for you to buy a couple spare servers and use those to verify Xen... hell, charge the customer an extra fee for the hardware required to verify their backups, if you can. For what it''s worth, I HAVE gotten this to work before: RHEL 5 / Xen Host -> RHEL 5 /Xen HVM guest -> rhel 5 PV domU And like I said, it was UGLY, and barely usable... but at least in the abstract sense, it does work... :-) _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
I used Xen PV inside Xen HVM for a lot of earlier XenFS development work. It''s a bit of a nasty hack though and given the typical response seems to be "Heh, that works, does it?" I don''t think it''s considered a "supported configuration" ;-) Cheers, Mark On Tuesday 03 March 2009 17:31:47 Jeff Lane wrote:> On Mon, Mar 2, 2009 at 9:23 AM, Heli <helicoterus-elih@yahoo.it> wrote: > > An hypervisor is able to run in a virtual machine if hypervisor > > construction and copmuter architecture meet the second Popek''s and > > Goldberg''s theorem (about recursive virtualization). > > Xen does not meet it, because x86 architecture is not a "perfect" > > virtualizable one. > > As has been said... yes you can. It''s not pretty, and certainly not > recommended. I''ve done it before using RHEL 5 and Xen running an > additional RHEL 5 HVM guest with Xen in that. It''s certainly ugly, > and incredibly slow, but you can at least log in and use it. > > Now, that being said, would I try that "in the real world": absolutely not. > Would I use that in your case of testing customer backups: No way... > > Sure it works, but it doesn''t work well, and I would not trust that to > verify a customer scenario. Best bet would be for you to buy a couple > spare servers and use those to verify Xen... hell, charge the customer > an extra fee for the hardware required to verify their backups, if you > can. > > For what it''s worth, I HAVE gotten this to work before: > > RHEL 5 / Xen Host -> RHEL 5 /Xen HVM guest -> rhel 5 PV domU > > And like I said, it was UGLY, and barely usable... but at least in the > abstract sense, it does work... :-) > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > Xen does not meet it, because x86 architecture is not a "perfect" > > virtualizable one. > > As has been said... yes you can. It''s not pretty, and certainly not > recommended. I''ve done it before using RHEL 5 and Xen running an > additional RHEL 5 HVM guest with Xen in that. It''s certainly ugly, > and incredibly slow, but you can at least log in and use it. > > Now, that being said, would I try that "in the real world": absolutely > not. Would I use that in your case of testing customer backups: No > way...I thought that might be the case. It would be nice if I could make a DomU think that it was a Dom0. It would need to be able to re-export block devices and network devices, and maybe create domains, although that wouldn''t be critical. Did the concept of ''driver domains'' ever come to pass? James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users