RE: [Xen-users] Automatic Loadbalancing via migration --live

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Denny Schierz
> Sent: 01 June 2007 12:22
> To: 'xen-users@xxxxxxxxxxxxxxxxxxx'
> Subject: [Xen-users] Automatic Loadbalancing via migration --live
> 
> hi,
> 
> how can tell Xen, to automatic live migrate VMs, if other hosts has
> nothing to do? I red somthing, that it is possible. Do i need 
> such other
>  tools like drdb or anything else?

You need to have some sort of tool that figures out when and where to
move the guest, and that tool will use "xm migrate -live some-domain
some-host". 

I think there are some other steps to allow the migration in the first
place - not sure what those are. 

And of course, for this to be at least somewhat meaningfull, you will
need to have the image file(s)/partitions that the guest is using for
disk-storage on a network-accessible place (e.g. a NFS, OCFS, SAN etc)

Note that for HVM guests, this is a new feature to 3.1.0, and I wouldn't
expect it to be entirely bug-free at the moment. In fact, I've submitted
three different fixes for problems that are caused by side-effects of
use of the save/restore mechanisms - which is also the code used for
migration. These patces are in the unstable tree. You can certainly
still use the save/restore/migrate functionality, but at some point,
these bugs will probably show their ugly head, unless you understand how
to avoid them (e.g. Save all guests, stop xend, remove xenstore
database, restart xend and restore guests again) - the other one that
will bite is if you try to migrate two guests at the very same moment in
time - once in a while it will fail to create the network interface due
to a race-condition inside the Dom0 Linux kernel (attempting to create
two Tap-interfaces with the same name - the second one failing of
course). 

--
Mats
> 
> cu denny
> 
> 



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