Re: [Qemu-devel] KVM call agenda for October 25

[Dor Laor <dlaor@redhat.com>]

On 10/25/2011 03:05 PM, Anthony Liguori wrote:
> On 10/25/2011 07:35 AM, Kevin Wolf wrote:
>> Am 24.10.2011 13:35, schrieb Paolo Bonzini:
>>> On 10/24/2011 01:04 PM, Juan Quintela wrote:
>>>>
>>>> Hi
>>>>
>>>> Please send in any agenda items you are interested in covering.
>>>
>>> - What's left to merge for 1.0.
>>
>> I would still like to cache the default cache mode (probably to
>> cache=writeback). We don't allow guests to toggle WCE yet which Anthony
>> would have liked to see before doing the change. Is it a strict
>> requirement?
>
> I don't see a way around it. If the default mode is cache=writeback,
> then we're open to data corruption in any guest where barrier=0. With
> guest togglable WCE, it ends up being a guest configuration issue so we
> can more or less defer responsibility.
>
> Do you think it's a good idea to change the default mode w/o guest WCE
> toggle support? What's your view about older guests if we change the
> default mode? What's your main motivation for wanting to change the
> default mode?
>
> I'd be much more open to changing the default mode to cache=none FWIW
> since the risk of data loss there is much, much lower.

A bit related to this, it would be nice to mark a VM un-migratable if 
cache!=none. Juan reports that currently it such VMs are exposed to data 
integrity issues so we need to fail migrating them automatically.

>
> Regards,
>
> Anthony Liguori
>
>>
>> Kevin
>>
>
>