[one-users] ONE server redundancy

[Tino Vazquez]

Hi Steven,

There may be incoherences between the two ONEs. Due to the cache (this
can be disabled in ONE, with performance penalty), two ONEs can have
the same VM record stored in memory, so if one instance of ONE writes
to the DB, these changes won't reflect in the other ONE until it
refreshes its caches, or worst still, the second instance of ONE may
overwrite the changes. I am by no means saying this is not achievable,
but there are several things (like the one in this email) to consider.

We have been thinking of a setup as the one you propose, and actually,
we would love to hear how this works in practice, as it is
theoretically possible but haven't got around to try it out.

Regards,

-Tino

--
Constantino Vázquez Blanco, MSc
OpenNebula Major Contributor  / Cloud Researcher
www.OpenNebula.org | @tinova79



On Wed, Feb 16, 2011 at 3:59 PM, Steven Timm <timm at fnal.gov> wrote:
> Tino--are you saying that there is state information in the oned
> that is not on disk at any given time?
> We were thinking of setting up an active-passive failover
> of our oned via heartbeat and DRBD. Is there any reason
> why that might not work?
>
> Steve Timm
>
>
> On Wed, 16 Feb 2011, Tino Vazquez wrote:
>
>> Hi Luis,
>>
>> That setup is not easily achievable. Operations are not transactional,
>> and also ONE keeps a cache, so the information of multiple  ONEs won't
>> be in sync.
>>
>> It can be achieved, but not out of the box, a fair amount of fiddling
>> is involved.
>>
>> Regards,
>>
>> -Tino
>>
>> --
>> Constantino Vázquez Blanco, MSc
>> OpenNebula Major Contributor  / Cloud Researcher
>> www.OpenNebula.org | @tinova79
>>
>>
>>
>> On Mon, Jan 31, 2011 at 6:15 PM, Luis M. Carril <lmcarril at cesga.es> wrote:
>>>
>>> Hello,
>>>    We have an OpenNebula installation and we wanted to deploy another ONE
>>> server for redundacy monitoring the same hosts and MVs. Could this be
>>> achieved if both ONE installations use the same mysql database? Are all
>>> the
>>> operations transactional?
>>>
>>> Cheers
>>>
>>> --
>>> Luis M. Carril
>>> Project Technician
>>> Galicia Supercomputing Center (CESGA)
>>> Avda. de Vigo s/n
>>> 15706 Santiago de Compostela
>>> SPAIN
>>>
>>> Tel: 34-981569810 ext 249
>>> lmcarril at cesga.es
>>> www.cesga.es
>>>
>>>
>>> ==================================================================
>>>
>>> _______________________________________________
>>> Users mailing list
>>> Users at lists.opennebula.org
>>> http://lists.opennebula.org/listinfo.cgi/users-opennebula.org
>>>
>> _______________________________________________
>> Users mailing list
>> Users at lists.opennebula.org
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>>
>
> --
> ------------------------------------------------------------------
> Steven C. Timm, Ph.D  (630) 840-8525
> timm at fnal.gov  http://home.fnal.gov/~timm/
> Fermilab Computing Division, Scientific Computing Facilities,
> Grid Facilities Department, FermiGrid Services Group, Group Leader.
> Lead of FermiCloud project.
>
>