[pve-devel] [PATCH] Use block storage migration for migration of KVM machines with local based storages

[Alexandre DERUMIER]

Hi, some news about disk migration,

it seem that the migration with migrate + blk , is the old way,
and can have problem when a lot of write occur

http://lists.gnu.org/archive/html/qemu-devel/2014-11/msg02727.html

So, the new way is to use nbd and drive mirroring
(I had sent some workflow last year, shouldn't be too difficult to implement)




----- Mail original ----- 

De: "Kamil Trzciński" <ayufan at ayufan.eu> 
À: "Alexandre DERUMIER" <aderumier at odiso.com> 
Cc: pve-devel at pve.proxmox.com, "Daniel Hunsaker" <danhunsaker at gmail.com> 
Envoyé: Mercredi 5 Novembre 2014 10:21:44 
Objet: Re: [pve-devel] [PATCH] Use block storage migration for migration of KVM machines with local based storages 


Yes 




On Wed, Nov 5, 2014 at 10:14 AM, Alexandre DERUMIER < aderumier at odiso.com > wrote: 


>>It was not very clear. Currently it works like for backups: vm is started in pause mode. 

Ok thanks. 
But is it also started if the storage is shared ? 



I'll look for nbd server, I think it could also be used to transfert unused disk. 
( http://manpages.ubuntu.com/manpages/precise/man8/qemu-nbd.8.html ) 


----- Mail original ----- 

De: "Kamil Trzciński" < ayufan at ayufan.eu > 
À: "Alexandre DERUMIER" < aderumier at odiso.com > 
Cc: pve-devel at pve.proxmox.com , "Daniel Hunsaker" < danhunsaker at gmail.com > 
Envoyé: Mercredi 5 Novembre 2014 10:10:38 


Objet: Re: [pve-devel] [PATCH] Use block storage migration for migration of KVM machines with local based storages 


It was not very clear. Currently it works like for backups: vm is started in pause mode. 


On Wed, Nov 5, 2014 at 9:30 AM, Alexandre DERUMIER < aderumier at odiso.com > wrote: 


>>- for stopped VM start it for migration 

I don't have reviewed the code yet, but is the VM started only in case of local storage (non-shared)? 

Because it don't make sense to start the vm and do memory migration, if the vm is stopped and storage is shared. 


Also, if the vm is stopped and storage is local, we can start the vm in pause mode (like for backup). 
Alternativily, I think it could be possible to start an nbd server on target node and use qemu-img convert to copy the disk. (vm offline) 






----- Mail original ----- 

De: "Daniel Hunsaker" < danhunsaker at gmail.com > 
À: "Kamil Trzciński" < ayufan at ayufan.eu > 
Cc: pve-devel at pve.proxmox.com 
Envoyé: Mercredi 5 Novembre 2014 01:48:15 
Objet: Re: [pve-devel] [PATCH] Use block storage migration for migration of KVM machines with local based storages 




On Nov 3, 2014 4:13 AM, "Kamil Trzcinski" < ayufan at ayufan.eu > wrote: 
> 
> - for stopped VM start it for migration 
This may not always be desired. For example, I often create VMs on one node, but don't want them to spin up until they're on another node. I create/maintain templates on an internal node which connects via OpenVPN to the public nodes, so my workflow makes more sense with create locally, migrate, then start, since my internal system isn't configured anywhere close to how my external systems are. Some of these systems wouldn't even start internally, since they rely on the host being set up how the external nodes are, and the internal node isn't set up that way. 
I guess what I'm saying is it would be good to at least have a node-level option to disable this step (starting VMs before migration is a sane default, just let me opt out). The more granularity the better, but there does come a point where options become excessive, so per-VM or per-migration disable might be overkill. 


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-- 

Kamil Trzciński 

ayufan at ayufan.eu 
www.ayufan.eu 






-- 

Kamil Trzciński 

ayufan at ayufan.eu 
www.ayufan.eu