On 09/27/2014 05:51 PM, Wido den Hollander wrote:
>
>
> On 27-09-14 11:00, Thierry Bernard wrote:
>> Dear CloudStack team,
>>
>> First let me introduce myself I am working for EasyVirt company around
>> the cloud and virtualization technologies.
>> Also in order to integrate CloudStack in one of our projects we need to
>> use the write-back cache disk feature.
>>
>> From this link it seems that this feature will be embedded in the next
>> release of CloudStack (4.5.0):
>> https://issues.apache.org/jira/browse/CLOUDSTACK-1302
>>
>> I tried from the master branch by creating a new disk offering and
>> setting the write cache type to write-back.
>> By generating a new instance with this new disk offerings the vm's xml
>> config file returns that the cache is "none".
>> Have you ever commits the code of this new feature?
>>
>
> Well, it should work (Shouldn't all code?), but you might run into a bug.
>
> If you set the loglevel to DEBUG of the KVM Agent you will see that the
> Management Server sends a StartCommand.
>
> Do you see the cache policy in there? What is it set to?
>
I tested this today with the 4.4.1 RC and it works for me with a RBD device:
<disk type='network' device='disk'>
<driver name='qemu' type='raw' cache='writeback'/>
<auth username='cloudstack'>
<secret type='ceph' uuid='822d3be5-3884-3700-8865-f45e7c752250'/>
</auth>
<source protocol='rbd'
name='cloudstack0/04192cec-715e-4ac6-b72e-3ed5980e5979'>
<host name='monitor' port='6789'/>
</source>
<target dev='vda' bus='virtio'/>
<alias name='virtio-disk0'/>
</disk>
Just be aware that your Compute Offering might be overriding the Disk
Offering. So you might want to check if the cache policy is writeback
there as well.
Wido
> Wido
>
>> In advance thank you for your help and your feedback.
>> Best regards,
>> Thierry Bernard.
>>
