[Gluster-devel] Default quorum for 2 way replication

[Bipin Kunal]

HI Pranith,

Thanks for starting this mail thread.

Looking from a user perspective most important is to get a "good copy"
of data.  I agree that people use replication for HA but having stale
data with HA will not have any value.
So I will suggest to make auto quorum as default configuration even
for 2-way replication.

If user is willing to lose data at the cost of HA, he always have
option disable it. But default preference should be data and its
integrity.

Thanks,
Bipin Kunal

On Fri, Mar 4, 2016 at 5:43 PM, Ravishankar N <ravishankar at redhat.com> wrote:
> On 03/04/2016 05:26 PM, Pranith Kumar Karampuri wrote:
>>
>> hi,
>>      So far default quorum for 2-way replication is 'none' (i.e.
>> files/directories may go into split-brain) and for 3-way replication and
>> arbiter based replication it is 'auto' (files/directories won't go into
>> split-brain). There are requests to make default as 'auto' for 2-way
>> replication as well. The line of reasoning is that people value data
>> integrity (files not going into split-brain) more than HA (operation of
>> mount even when bricks go down). And admins should explicitly change it to
>> 'none' when they are fine with split-brains in 2-way replication. We were
>> wondering if you have any inputs about what is a sane default for 2-way
>> replication.
>>
>> I like the default to be 'none'. Reason: If we have 'auto' as quorum for
>> 2-way replication and first brick dies, there is no HA.
>
>
>
> +1.  Quorum does not make sense when there are only 2 parties. There is no
> majority voting. Arbiter volumes are a better option.
> If someone wants some background, please see 'Client quorum' and 'Replica 2
> and Replica 3 volumes' section of
> http://gluster.readthedocs.org/en/latest/Administrator%20Guide/arbiter-volumes-and-quorum/
>
> -Ravi
>
>> If users are fine with it, it is better to use plain distribute volume
>> rather than replication with quorum as 'auto'. What are your thoughts on the
>> matter? Please guide us in the right direction.
>>
>> Pranith
>
>
>