Xen users - Jan 2010 - VM checkpoint/restart and migration

Hi,

i am quite new to Xen, I want to do some experiments and I would like to
know the followings regarding some of the Xen Hypervisor features:

*Context A: *2 hosts in the same LAN, 2 VMs on top of each host and a NFS
storage with the disk images between the hosts. Host 1 contains VM1 and VM2
and Host 2 contains VM3 and VM4. All VMs have private IPs.
1. Save/restore: I run an application that was communicating with all 4 VMs
in the same time. I suspended the application and I saved the state of VM1
to the shared storage and than restart VM1 from that file on top of Host2.
Than I resumed the application and it continued it''s execution
successfully.
So this means that the connections were preserved.

2. Live migration: same thing. Application communicating with all 4 VMs and
I migrated a VM to another host and all the connections were preserved.
*
Context B: *2 hosts in the same LAN, 2 VMs on top of each host and *no* NFS
storage. All VMs have private IPs.
3. Save/restore: Can I save the state of a VM on one host and then restore
it to a new host without having a shared device between the 2 hosts (maybe
if I copy the disk image to the new host)? If an application is running on
it are the connections going to be preserved?

*Context C*: 2 hosts in different subnet, no NFS storage, VMs having public
IPs from different subnet
 4. Is there any way that I can save the state of a VM on Host1 and than
restart it on Host2? And more than that, is it possible to preserve the
network connections?

I would really appreciate an answer for question 3 and 4,

Thanks a lot,
Andreea


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Andreea Costea schrieb:
> Hi,
>
> i am quite new to Xen, I want to do some experiments and I would like 
> to know the followings regarding some of the Xen Hypervisor features:
>
> *Context A: *2 hosts in the same LAN, 2 VMs on top of each host and a 
> NFS storage with the disk images between the hosts. Host 1 contains 
> VM1 and VM2 and Host 2 contains VM3 and VM4. All VMs have private IPs.
> 1. Save/restore: I run an application that was communicating with all 
> 4 VMs in the same time. I suspended the application and I saved the 
> state of VM1 to the shared storage and than restart VM1 from that file 
> on top of Host2. Than I resumed the application and it continued
it''s
> execution successfully. So this means that the connections were 
> preserved.
Interesting. An application should have some kind of timeout for open 
sessions; in any case this depends very much on how the app handles 
this. This test delivers by no means a valuable general result (sorry 
for hitting into it so directly).

You have to test this separately for every application you plan to deploy.

Dirk


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