Re: [Xen-users] live migration with Xen

[Luke S Crawford <lsc@xxxxxxxxx>]

"XUFENG" <xufengnju@xxxxxxxx> writes:
> On Xen v3.0 Users' Manual it has the part "8.2 Migration and Live Migration".
> But if the primary physical machine suddenly crashed,we will not be able to 
> do 
> live migration.Is it right?

Yes.

> I mean,can Xen have the same function as Vmware esx server's vmotion

I believe vmotion does almost exactly what live migration does, that is, move
from one running, healthy hoast to another.  It is ... difficult to copy
bits out of ram when the server is dead.  

> (when the primary physical machine crashed,the virtual hosts on it can be 
> automatically migrated to the second Vmware esx server)?

I forget what VMWARE calles this, but I'm pretty sure it's not vmotion.
Also, for this to work in vmware, you need the second server up and running
in 'hot standby' mode.   From what I understand, the memory state of the second
image is kept approximately the same as the first image;  this is how it
avoids the problem of copying bits out of ram on the dead server.  

In some cases, it's quite useful;  but it's not free.  you are using two servers
to get the work of one server. 

similar features, I believe, are planned for the Xen 3.4 release.   As of now, 
though, with the default hypervisor, there is no such functionality in xen.  

check out 

http://www.usenix.org/events/nsdi/tech/full_papers/cully/cully_html/index.html

for some info.  

-- 
Luke S. Crawford
http://prgmr.com/xen/  -   Hosting for the technically adept
                           We don't assume you are stupid.  

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users