[one-users] iSCSI recipe

[Gary S. Cuozzo]

Is there a reason that ONE can't call a TM script with the source host, dest host, vm template, etc. when the migrate command is executed? 

While ONE can't orchestrate the migration, it can at least notify the TM of the migration in advance. That would allow me to grab the info I need from the template and fire off the login or rescan on the dest host. ONE has got to know this info in order to even notify libvirt/KVM to do the migration. So just call a TM script before issuing the libvirt command and abort if the script returns error. 

Logout is not as critical to me. Worst case I have some hosts which iSCSI sessions which are not in use. The ideal scenario would be to be able to have some sort of TM script that gets called after ONE detects successful migration, but I could work around that on my own if it were not the case. 

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

From: "Ruben S. Montero" <rsmontero at opennebula.org> 
To: "Gary S. Cuozzo" <gary at isgsoftware.net> 
Cc: users at lists.opennebula.org 
Sent: Thursday, August 16, 2012 11:28:27 AM 
Subject: Re: [one-users] iSCSI recipe 

Note that OpenNebula cannot orchestrate the two libvirt/KVM hypervisors doing the migration. When the first host is ready to stop running the VM (memory has been sent to the second hypervisor, etc..) it executes the hook (logout from the iSCSI server) and just right before starting rhe VM in the second host the hook (login in the iSCSI server) is run. There is nothing we can do to hook in that process. 


We could however, include such scripts as part of the TM, distribute them in the hosts, and put them in the right places... 




Cheers 











On Thu, Aug 16, 2012 at 1:48 PM, Gary S. Cuozzo < gary at isgsoftware.net > wrote: 




Thanks. While I understand that the login/logout needs to happen on the host systems, I think that if ONE had it's own hook or, better IMO, a TM script that could be called before/after migration, the functionality could be contained within the drivers themselves. Then I could just take my code (which is now sprinkled across several host machines) and put it in the TM where I think it better fits. My DS/TM already make remote calls via SSH to the SAN & vm hosts, so this would still fit the model pretty nicely. 

I seem to remember that if the similar events for non-persistent images were called for persistent ones, I would be able to accomplish what I want. 

Let me know your thoughts. 

Thanks, 
gary 




From: "Ruben S. Montero" < rsmontero at opennebula.org > 
To: "Gary S. Cuozzo" < gary at isgsoftware.net > 
Cc: users at lists.opennebula.org 
Sent: Thursday, August 16, 2012 5:55:57 AM 
Subject: Re: [one-users] iSCSI recipe 

Hi 


For live-migrations the supported procedure is the libvirt hook, note that live migrations requires a close synchronization between the image movements, memory movements and the hypervisors. OpenNebula cannot perform the login/logout from the iSCSI sessions there. Cold migrations are handled by opennebula as part of the save and restore commands. 


Cheers 


Ruben 


On Sun, Aug 12, 2012 at 4:41 AM, Gary S. Cuozzo < gary at isgsoftware.net > wrote: 

<blockquote>


Hello, 



<blockquote>


<blockquote>
* Each host needs to attach to all iSCSI targets that are needed by 
guests running on the host. It's not entirely clear to me if ONE handles 
all that or not (assuming it does). 



ONE handles this by login/logout in an iSCSI session as needed 


</blockquote>

My iSCSI setup uses a target for each virtual server, and multiple LUN's per target (if the server has multiple disks). I developed a custom driver for it. I don't know if I have a shortcoming in my driver, or maybe a config issue on ONE, but I found that ONE did NOT handle the login/logout on the host machines. It was fine for the initial setup & deployment of the vm, but live migrations did not cause my driver to initiate a login on the receiving host and a logout on the transferring host. 

I ended up having to write a libvirt hook which scanned for new targets to log them in. It also rescanned all current targets to check if they had new LUN's attached to them. It works well and my vm's migrate just fine, but I would prefer to have all this handled within ONE. 

What is the script that ONE calls in order to initiate the logins/logouts as vm's migrate? 

Cheers, 
gary 



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-- 
Ruben S. Montero, PhD 
Project co-Lead and Chief Architect 
OpenNebula - The Open Source Solution for Data Center Virtualization 
www.OpenNebula.org | rsmontero at opennebula.org | @OpenNebula 


</blockquote>


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</blockquote>




-- 
Ruben S. Montero, PhD 
Project co-Lead and Chief Architect 
OpenNebula - The Open Source Solution for Data Center Virtualization 
www.OpenNebula.org | rsmontero at opennebula.org | @OpenNebula 

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