[one-users] TM question about rescheduling a vm

[Gary S. Cuozzo]

Odd, that's not the behavior I'm seeing. When I issue a "onevm resched <id>" I am seeing the VM get suspended, a checkpoint file created, then the scheduler attempts to migrate the VM. The pre/postmigrate scripts never get called for my TM driver, my NFS mount points don't get created on the target host, and the migration fails. I then have to delete the VM and reschedule from scratch. 

I just verified this using a VM with a single, persistent, disk in my NFS datastore. The flow I see in the logs is: 
1. VM gets flagged for reschedule 
2. VM gets saved: " Successfully execute virtualization driver operation: save." 
3. VM gets cleaned: " Successfully execute network driver operation: clean." 
4. ONE looks like it stages the VM on the target host: " Successfully execute network driver operation: pre." 
5. VM fails to restore: " Command execution fail: /var/tmp/one/vmm/kvm/restore /var/lib/one//datastores/0/72/checkpoint" 
" Command "virsh --connect qemu:///system restore /var/lib/one//datastores/0/72/checkpoint" failed: error: Failed to restore domain from /var/lib/one//datastores/0/72/checkpoint" 
" error: Unable to allow access for disk path /var/lib/one//datastores/0/72/disk.0: No such file or directory" 

At this point, the VM is failed state and I have to resubmit it. 

I am able to live migrate this VM just fine and expected that rescheduling it should also have done a live migration. For some reason, it is doing a plain migration. 

Either way, is there a reason the TM pre/post migrate script is not getting called as it would for a live migration? It seems like I either have something misconfigured, or there is a bug. Either way I would expect the pre/postmigrate scripts to be called. 

Thanks for any help, 
gary 

----- Original Message -----

From: "Carlos Martín Sánchez" <cmartin at opennebula.org> 
To: "Gary S. Cuozzo" <gary at isgsoftware.net> 
Cc: users at lists.opennebula.org 
Sent: Wednesday, December 12, 2012 10:07:12 AM 
Subject: Re: [one-users] TM question about rescheduling a vm 

Hi, 


There is no 'resched' driver action, the command just marks the VM to be rescheduled. The scheduler then migrates or live-migrates these VMs depending on the LIVE_RESCHED attribute of sched.conf [1] 


Regards 


[1] http://opennebula.org/documentation:rel3.8:schg 

-- 
Carlos Martín, MSc 
Project Engineer 
OpenNebula - The Open-source Solution for Data Center Virtualization 
www.OpenNebula.org | cmartin at opennebula.org | @OpenNebula 



On Tue, Dec 11, 2012 at 8:32 PM, Gary S. Cuozzo < gary at isgsoftware.net > wrote: 




Hello, 
I have developed my own TM driver for a NFS based datastore using ZFS. It works well so far, except in the case of using the "onevm resched <id>" command. 

The failure happens because my TM relies on pre/postmigrate scripts to mount/umount ZFS datastores on the hosts as vm's move around. In the case of the resched command, the pre/postmigrate scripts don't get called, so the vm cannot start on the target host because the disk images are not available. 

In my use case, there isn't much difference between the live migration and the saveas/checkpoint way the resched works. Can the pre/postmigrate scripts be called for the resched? If not, is there some other way I can get them called so I can setup/teardown my nfs mounts? 

Thanks for any help, 
gary 


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