[ovirt-devel] vdsm disabling logical volumes

[Itamar Heim]

On 05/13/2014 03:16 AM, Jiri Moskovcak wrote:
> On 05/12/2014 05:27 PM, Dan Kenigsberg wrote:
>> On Mon, May 12, 2014 at 02:04:05PM +0200, Jiri Moskovcak wrote:
>>
>>>>>> Jiri, could you describe why you keep your LV active, but not open?
>>>>>>
>>>>>
>>>>> - the setup flow goes approximately like this:
>>>>>
>>>>> 1. create the LVs for the hosted-engine
>>>>> 2. install the engine into the VM
>>>>> 3. add the host to the engine
>>>>>    - this causes re-deploy of vdsm and deactivating the LVs
>>>>> 4. start the ha-agent and ha-broker services which uses the LVs
>>>>>
>>>>> - I guess we could move the creation of the LVs after the vdsm is
>>>>> re-deployed, just before the HE services are started, but it won't
>>>>> fix the problem if the vdsm is restarted
>>>>
>>>> It's not going to solve our design problem, but can the users of
>>>> that LV
>>>> activate it just before they open it? This way there's only a small
>>>> window where vdsm can crash, restart, and deactivate the LV.
>>>>
>>>
>>> - no, it runs as vdsm user and as it seems only root can activate LVs
>>> and
>>> during the startup when it still has the root privs, it doesn't know
>>> anything about the storage, the storage is connected on a client request
>>> when it already doesn't have root privs
>>
>> Vdsm uses "sudo" for these purposes.
>
> - that would solve the problem with privs, but I would really like to
> avoid the situation where the vdsm disables the LVs as there is no
> reason for disabling it as there can be situation where vdsm is down and
> the VM with the engine is still running ok
>
>>
>>> - we could use vdsm to activate the LV if it provides API which
>>> allows that
>>
>> There's the undocumented prepareImage(), but please do not use it before
>> an ack by the storage team.
>>
>
> - sure, I'm working on it with Nir now, I won't do anything without the
> storage team approval ;)
>
>> Dan.
>>
>
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I'm missing something here - why doesn't VDSM knows about this LV? its a 
VM started by VDSM?