[Kimchi-devel] [PATCH] bug fix: setup disks to use cache=none to support live migration.

[Shu Ming]

于 2014/3/6 8:46, Royce Lv 写道:
> On 2014年03月05日 23:51, Paulo Vital wrote:
>> When executing a virsh live migration of a VM created by Kimchi, the
>> migration stops due to miss configuration "cache=none" on disk's
>> performance parameters.
> I'm little worried about make cache 'none' will cause performance 
> downgrade for guest in daily running.
> Can we allow update this parameter in vm disk edit and change it when 
> we decide to live migrate a vm?

Agree.  I can imagine the bad performance with disk's cache off. Can we 
re-enable it after the VM migrated?

>>
>> Signed-off-by: Paulo Vital <pvital at linux.vnet.ibm.com>
>> ---
>>   src/kimchi/vmtemplate.py | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/kimchi/vmtemplate.py b/src/kimchi/vmtemplate.py
>> index e2d78a4..89b5e72 100644
>> --- a/src/kimchi/vmtemplate.py
>> +++ b/src/kimchi/vmtemplate.py
>> @@ -152,7 +152,7 @@ class VMTemplate(object):
>>               params = {'src': src, 'dev': dev, 'bus': 
>> self.info['disk_bus']}
>>               ret += """
>>               <disk type='file' device='disk'>
>> -              <driver name='qemu' type='qcow2'/>
>> +              <driver name='qemu' type='qcow2' cache='none'/>
>>                 <source file='%(src)s' />
>>                 <target dev='%(dev)s' bus='%(bus)s' />
>>               </disk>
>> @@ -182,7 +182,7 @@ class VMTemplate(object):
>>           # Passthrough configuration
>>           disk_xml = """
>>               <disk type='volume' device='lun'>
>> -              <driver name='qemu' type='raw'/>
>> +              <driver name='qemu' type='raw' cache='none'/>
>>                 <source dev='%(src)s'/>
>>                 <target dev='%(dev)s' bus='scsi'/>
>>               </disk>"""
>
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