LinuxXenServer

XenCenter – live migrating a vm in a pool to another host

When migrating a vm server from one host to another host in the pool I found it to be very easy at first.

In fact,  it was one of the first things test I did after setting up my first vm on a host in a pool. 4 steps

1. Simply right click on the vm in XenCenter ->
2. Migrate to Server ->
3. Select from your available servers.
4. Follow the wizzard

In building some servers,  I wanted to get some base templates which are ‘aware’ of the network I am putting together.  This would involve adding some packages and configuration,  taking a snapshot and then turning that snapshot into a template that I could easily restart next time I wanted a similar server.  Then when I went to migrate one of the servers into its final resting place.  I found an interesting error.

1. Right click on the vm in XenCenter ->
2. Migrate to Server ->
3. All servers listed – Cannot see required storage

I found this odd since I was sure that the pool could see all of the required storage (In fact I was able to start a new VM on the storage available,  so I new the storage was there)

I soon found out though that the issue is that the live migrate feature,  just doesnt work when there is more than one snapshot.  I will have to look into my snapshot management on how I want to do this now,  but basically I found that by removing old snapshots does to where the VM only had one snapshot (I left one that was a couple of days old) I was able to follow the original 4 steps

 

Note:  the way I found out about the limitation of the number of snapshots was by

1. Eight click on the vm in XenCenter ->
2. Migrate to Server ->
3. The available servers are all grayed out,  so Select “Migrate VM Wizard”
4. In the wizard that comes up select the current pool for “Destination”
5. This populates a list of VMs with Home Server in the destination pool want to migrate the VM (My understanding,  is that this will move the VM to that server AND make that new server the “Home Server” for that VM)
6. When you attempt to select from the drop down list under Home Server,  you see a message “You attempted to migrate a VM with more than one snaphot”

Using that information I removed all but one snapshot and was able to migrate.  I am sure there is some logical reason behind snapshot / migration limitation but for now I will work around it and come up with some other way to handle my snapshots than just leaving them under the snapshot tab of the server.