Open Stack

> Why would ephemeral instance disks be copied if the backing store is  
> a shared system like Ceph.

Sorry for the confusion, I tried to describe the workflow if you use  
local disk storage for the instances. Of course there's no disk  
copying if you use a storage like ceph.


Zitat von Jay Pipes <jaypipes at gmail.com>:

> On 01/25/2017 03:19 AM, Eugen Block wrote:
>> All these instances are in our ceph cluster.
>>
>> The instance path is defined in nova.conf:
>>
>> # Where instances are stored on disk (string value)
>> instances_path = $state_path/instances
>>
>> If one compute node fails but it's able to initiate a migration, the
>> same instance directory is created on the new host and the disks are
>> copied to its new compute node.
>
> Why would ephemeral instance disks be copied if the backing store is  
> a shared system like Ceph. There would be no need to copy a disk  
> image since the destination host's /var/lib/nova/instances directory  
> is exactly the same as the source's, right?
>
> Best,
> -jay
>
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