[ovirt-devel] vdsm disabling logical volumes

[Jiri Moskovcak]

On 05/14/2014 02:57 AM, Itamar Heim wrote:
> 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?

- these LVs are created by hosted-engine-setup and are not connected 
with the VM

--Jirka