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Re: [virt-tools-list] Live migration of iscsi based targets



On 10/28/2010 06:06 AM, Mark van Walraven wrote:
> On Wed, Oct 27, 2010 at 11:10:25AM +0200, Gildas Bayard wrote:
>> My understanding is that blade A got it's iscsi disk cache up and  
>> running and that when the VM comes back, blade A has no way to know that  
>> the VM got its disk altered by its stay on blade B for a while. Hence  
>> the corruption.
> 
> Another possible reason is caching by KVM.  Check in the <disk> element
> of the domain definition for one like:
> 
>       <driver name='qemu' cache='none'/>
> 
> Without it, KVM defaults to 'writethrough' caching, which is not safe
> for migration.

Gildas, are you ok to check this setting and let us know if it helps
you?

This one setting seems like it's what you might need, and could be
a simple fix.  It *might* affect your virtual machine's performance
though. (not sure)

Phil's end-to-end configuration sounds really useful too, but a
bit more involved to adapt if there's an easy fix. :)






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