I planned to play around a bit with XEN on my P3 machine. Before I go on, I still have several questions that involve the planning phasis. -What about module loading in domU kernels? I know that it won''t success with hardware related drivers, but is it possible to load "pure software drivers" like iptables? Reboot the dom0 system while running domU systems? I''m not sure how equal the dom0 system is to the domU ones, but as long as the hypervisor isn''t stopped, can dom0 be rebooted without interrupt of the domU systems? Would it be possible on hardware-supported virtualisation versions of the hypervisor, as with Vanderpool of Pacifica? How many virtual eths per one physical one do you recommend? If have a 100mbps card PCI built in my box. This should suffice for about 4-5 systems, shouldn''t it? Furthermore, how is routing approached by default? I''ve read some docs about it, but didn''t really understand it in it''s entirety. Is there already some L2-routing so I wouldn''t need to connect a cable into the physical device or are all packets sent to a router, hence L3? Is there a way booting a domU (or more likely an installer for a future domU) from CD? If not, it would be necessary to first set all systems up "xenlessly" and then adapt all them to run on XEN. In hope of not to have asked some silly questions, F. Sidler _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Am Donnerstag, 9. März 2006 00:10 schrieb Fabiano Sidler:> I planned to play around a bit with XEN on my P3 machine. Before I go on, > I still have several questions that involve the planning phasis. > > -What about module loading in domU kernels? > I know that it won''t success with hardware related drivers, but is it > possible to load "pure software drivers" like iptables?Yes sure, software modules are handled like in normal kernels. In xen-unstable there are also already patches to pass PCI devices to domU''s. (I''m sending this mail via a domU with a delegated physical NIC ;-) )> > Reboot the dom0 system while running domU systems? > I''m not sure how equal the dom0 system is to the domU ones, but as long as > the hypervisor isn''t stopped, can dom0 be rebooted without interrupt of > the domU systems? Would it be possible on hardware-supported virtualisation > versions of the hypervisor, as with Vanderpool of Pacifica?Not possible, because the hypervisor need''s userspace tools like xend to run domU''s. I guess VT et. al. won''t change that. general architecture.> > How many virtual eths per one physical one do you recommend? If have a > 100mbps card PCI built in my box. This should suffice for about 4-5 > systems, shouldn''t it?Depends on your network load, but for testing purpose: sure.> Furthermore, how is routing approached by default?default is bridging.> I''ve read some docs about it, but didn''t really understand it in it''s > entirety. Is there already some L2-routing so I wouldn''t need to connect > a cable into the physical device or are all packets sent to a router, > hence L3?See this documentation about xen and shorewall, it explains the architecture very well: http://www.shorewall.net/XenMyWay.html> > Is there a way booting a domU (or more likely an installer for a future > domU) from CD? If not, it would be necessary to first set all systems up > "xenlessly" and then adapt all them to run on XEN.Set up one system and from that system you create the domU''s with your distros installer tools. e.g. SuSE''s Yast dirinstall mode After that you''ll xenify them by installing xen in your dom0, creating xenU''s config files and copying the modules into the partition image or physical device/partition or lvm. Check the xen-wiki for Howtos HTH, Alex _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Alexander Wilms > Sent: 08 March 2006 23:48 > To: xen-users@lists.xensource.com > Subject: Re: [Xen-users] Several XEN questions > > Am Donnerstag, 9. März 2006 00:10 schrieb Fabiano Sidler: > > I planned to play around a bit with XEN on my P3 machine. > Before I go > > on, I still have several questions that involve the planning phasis. > > > > -What about module loading in domU kernels? > > I know that it won''t success with hardware related drivers, > but is it > > possible to load "pure software drivers" like iptables? > Yes sure, software modules are handled like in normal kernels. > In xen-unstable there are also already patches to pass PCI > devices to domU''s. > (I''m sending this mail via a domU with a delegated physical NIC ;-) ) > > > > > Reboot the dom0 system while running domU systems? > > I''m not sure how equal the dom0 system is to the domU ones, but as > > long as the hypervisor isn''t stopped, can dom0 be rebooted without > > interrupt of the domU systems? Would it be possible on > > hardware-supported virtualisation versions of the > hypervisor, as with Vanderpool of Pacifica? > Not possible, because the hypervisor need''s userspace tools > like xend to run domU''s. I guess VT et. al. won''t change > that. general architecture.Most importantly, the HVM (VT/SVM) guest would rely on qemu-dm, which lives in Dom0. And there''s currently no way to reboot Dom0 without also reloading Xen, so the first problem would be to disconnect Dom0 from Xen. If you loose Xen, then NO DomU would work at all, obviously. There is work going on with kexec, which will allow you to replace the Linux kernel without rebooting. This MAY solve the problem [but I''m not sure how far along the kexec work has got]. Here''s some info on kexec under Linux [I haven''t read all of it, I just googled for kexec - there may be better material, I got MANY hits]: http://www-128.ibm.com/developerworks/linux/library/l-kexec.html Whilst it would potentially be possible to do so, it would make much more sense to shuffle DomU to a second machine using the migration features in Xen, then reboot/replace Dom0 on the first machine. Admittedly, migration, I think, is still broken on HVM systems, but it''s certainly meant to work at some future point in time. Migration will of course stop the domain for a brief moment, so if you want five nines service availability, you''ll have to combine this with some other fail-over technology, like having two servers running the same DomU in parallell or some such. [In which case it may not be needed to move the DomU in the first place, of course]. If you view the Dom0 as part of the Operating System, and DomU''s as "applications", then it becomes more clear. -- Mats _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users