[PVE-User] Ris: Ceph MON quorum problem

[Fabrizio Cuseo]

Answer following:

----- Il 16-set-19, alle 14:49, Ronny Aasen ronny+pve-user at aasen.cx ha scritto:

> with 2 rooms there is no way to avoid a split brain situation unless you
> have a tie breaker outside one of those 2 rooms.
> 
> Run a Mon on a neutral third location is the quick, correct, and simple
> solution.
> 
> Or
> 
> you need to have a master-slave situation where one room is the master
> (3 mons) and the other room is the slave (2 mons) and the slave can not
> operate without the master, but the master can operate alone.


Yes, I need a master-slave situation, but I need to have the slave running in case of master's fault.
So, if a have a total of 3 mons (2 on master, 1 on slave), if I loose the master, I have only 1 mon available, and i need to create another mon (but i can't create it because I have no quorum).

I know that for now, the only solution is a third room.

Thanks, Fabrizio 




> 
> On 14.09.2019 16:11, f.cuseo at panservice.it wrote:
>> This is My last choice :)
>> Inviato dal mio dispositivo Huawei
>> -------- Messaggio originale --------
>> Oggetto: Re: [PVE-User] Ceph MON quorum problem
>> Da: "Brian :"
>> A: Fabrizio Cuseo ,PVE User List
>> CC:
>> 
>> 
>> Have a mon that runs somewhere that isn't either of those rooms.
>> 
>> On Friday, September 13, 2019, Fabrizio Cuseo <f.cuseo at panservice.it> wrote:
>>> Hello.
>>> I am planning a 6 hosts cluster.
>>>
>>> 3 hosts are located in the CedA room
>>> 3 hosts are located in the CedB room
>>>
>>> the two rooms are connected with a 2 x 10Gbit fiber (200mt) and in each
>> room i have 2 x 10Gbit stacked switch and each host have a 2 x 10Gbit (one
>> for each switch) for Ceph storage.
>>>
>>> My need is to have a full redundancy cluster that can survive to CedA (or
>> CedB) disaster.
>>>
>>> I have modified the crush map, so I have a RBD Pool that writes 2 copies
>> in CedA hosts, and 2 copies in CedB hosts, so a very good redundancy (disk
>> space is not a problem).
>>>
>>> But if I loose one of the rooms, i can't establish the needed quorum.
>>>
>>> Some suggestion to have a quick and not too complicated way to satisfy my
>> need ?
>>>
>>> Regards, Fabrizio
>>>
>>>
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