Hi, This question perhaps should be better posted on linux-ha but... it seems that Suse 10 SP1 allows to migrate Xen VMs between Heartbeat nodes using live migration, where other distros just stop them on a node and start them on another node. Does anybody succeeded in doing the same thing with another GNU/Linux distribution ? I''m really interested in finding such a feature. Thanks for any clue. -- Yann Cezard _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, > it seems that Suse 10 SP1 allows to migrate Xen VMs between Heartbeat > nodes using live migration, where other distros just stop them on a > node and start them on another node. I don''t see any sense to use live migration to get up and running a system that fails on an other node! If heartbeat does not response anymore I assume that either the dom0 with all domUs crashed, so a migration of any domU is not possible at all, or the specific domU is dead and you will get a dead domU on the new system after migration too (I don''t know if you can migrate a dead system)! So if the "source" system does not answer anymore, the only way to get it up and running is to start it again on the same or on a different node. Live migration is only good for load balancing and planned maintanance issues, not for high availability! -- Chau y hasta luego, Thorolf _______________________________________________ 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 > Yann Cezard > Sent: 03 July 2007 09:25 > To: xen-users@lists.xensource.com > Subject: [Xen-users] Xen, Heartbeat2 and live migration > > Hi, > > This question perhaps should be better posted on linux-ha but... > it seems that Suse 10 SP1 allows to migrate Xen VMs between Heartbeat > nodes using live migration, where other distros just stop > them on a node > and start them on another node.Whilst this MAY be true, I find it unlikely that there is any difference between SuSE and other Linux distros. The key parts of Live Migration (or any other migration) is done by Xen-supplied code. It is of course possible that SuSE 10 SP1 has newer code than many of the other distros, which of course would help the matter. Of course, if a node goes down in such a setup, the guests on that node most likely can''t be migrated, but have to be restarted from the original config files - because if the machine has failed, it''s not likely to be "alive enough" to support migration. This of course also means that the "heartbeat" case is pretty much a irrelevant factor [although of course, it depends on how you use heartbeat - in the guest, or in dom0 (or both?). If it''s in the guest, I don''t see why it wouldn''t work, as long as you have a reasonable timeout for heartbeat - the guest domain will be down for some dozen of milliseconds or so - perhaps 100ms, so if you don''t tolerate that sort of downtime in heartbeat, then it''s not going to work, and if you''re planning to run this sort of setup, it''s probably good to make some tests on how long the downtime is, and make sure that the "server is dead" time about 2-3 times longer than the worst measured downtime for a successful migration]. -- Mats _______________________________________________ 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 > Thorolf Godawa > Sent: 03 July 2007 10:09 > To: xen-users@lists.xensource.com > Subject: Re: [Xen-users] Xen, Heartbeat2 and live migration > > Hi, > > > it seems that Suse 10 SP1 allows to migrate Xen VMs > between Heartbeat > > nodes using live migration, where other distros just stop them on a > > node and start them on another node. > I don''t see any sense to use live migration to get up and running a > system that fails on an other node! > > If heartbeat does not response anymore I assume that either the dom0 > with all domUs crashed, so a migration of any domU is not possible at > all, or the specific domU is dead and you will get a dead domU on the > new system after migration too (I don''t know if you can > migrate a dead > system)! > > So if the "source" system does not answer anymore, the only > way to get > it up and running is to start it again on the same or on a > different node. > > Live migration is only good for load balancing and planned > maintanance > issues, not for high availability!I completely agree with all the above. -- Mats> -- > > Chau y hasta luego, > > Thorolf > > _______________________________________________ > 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
Thorolf Godawa a écrit :> Hi, > > > it seems that Suse 10 SP1 allows to migrate Xen VMs between Heartbeat > > nodes using live migration, where other distros just stop them on a > > node and start them on another node. > I don''t see any sense to use live migration to get up and running a > system that fails on an other node! > > If heartbeat does not response anymore I assume that either the dom0 > with all domUs crashed, so a migration of any domU is not possible at > all, or the specific domU is dead and you will get a dead domU on the > new system after migration too (I don''t know if you can migrate a dead > system)! > > So if the "source" system does not answer anymore, the only way to get > it up and running is to start it again on the same or on a different > node. > > Live migration is only good for load balancing and planned maintanance > issues, not for high availability!I totally agree with that. It''s OK for HA, but what i want is to be able to planned maintenance on dom0, and so migrating domU on another node. If I do that with "xm migrate --live ..." heartbeat will see that the resource (the domU) has moved, and it will stop it on the new node, and start it again on the first one. That is definitly not what I want (or perhaps i am missing something ?). Heartbeat2 allows to migrate resource (Xen domU in our case) from one node to another. But how it works is : it stops the domU on nodeX (one of our dom0 in the HB2 cluster), and starts on nodeY. A simple modification of the Xen script to use xen live migration in this case seems not to be sufficient, as there is no way to know the destination node in it (or we could hard code the destination in the script, but that is a dirt hack, I don''t want that). I think that is where Novell/Suse has done modifications in HB2 code in order to allow that (a way to know the destination node when migrating resource), and that''s what I would like to achieve, but without using Novell/Suse. But perhaps I should better ask on linux-ha mailing list. I just wanted to know if someone here has already done such a thing, or using Suse 10 SP1. Cheers, -- Yann Cezard _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Yann Cezard a écrit :> Hi, > > This question perhaps should be better posted on linux-ha but... > it seems that Suse 10 SP1 allows to migrate Xen VMs between Heartbeat > nodes using live migration, where other distros just stop them on a node > and start them on another node. > > Does anybody succeeded in doing the same thing with another GNU/Linux > distribution ? > > I''m really interested in finding such a feature. > > Thanks for any clue. >Ok, I will answer to myself, in case someone else could be interested in such a feature : Using the Heartbeat-2 2.1 devel version, live migration is possible. To enable live migration : crm_resource -r your_domU_resource --meta -p allow_migrate -v true And then to migrate : crm_resource -M -r your_domU_resource -H your_destination_node Hope this will help someone else. -- Yann Cezard _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
You can do live migration only with paravirtualized domU with hvm you can do migration but not live, since the xen 3.1 . It''s very easy to do heartbeat script with an xm command. I have made a H.A xen server ( with 4 servers ) : - Xen - Heartbeat - drbd - iscsi Regards Yves aka Nantes_geek ------------------------------------------------------------------------ IF YOU SPEAK FRENCH : WELCOME IN THE FRENCH XEN CHANNEL : zelazny.freenode.net #xenfr ------------------------------------------------------------------------ _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > Of course, if a node goes down in such a setup, the guests on thatnode> most likely can''t be migrated, but have to be restarted from the > original config files - because if the machine has failed, it''s not > likely to be "alive enough" to support migration.I''ve thought about using Heartbeat to manage domains across various nodes - my biggest fear is that if something went wrong in just the right way your domain might start on one node while it was already running on another, with the result of completely hosing all the filesystems involved. The only really bulletproof way around this would be for heartbeat to be able to tell the SAN to only export the block device for that domain to the active node, and it all becomes a bit complicated... James _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users