[Tarantool-patches] [RFC] Quorum-based synchronous replication
Sergey Ostanevich
sergos at tarantool.org
Tue Apr 14 17:43:08 MSK 2020
Hi!
Thanks for review!
On 14 апр 15:58, Sergey Bronnikov wrote:
> Hi,
>
> see 5 comments inline
>
> On 00:08 Sat 04 Apr , Sergey Ostanevich wrote:
> >
> > * **Status**: In progress
> > * **Start date**: 31-03-2020
> > * **Authors**: Sergey Ostanevich @sergos \<sergos at tarantool.org\>
> > * **Issues**:
>
> 1. Just for convenience, please add https://github.com/tarantool/tarantool/issues/4842
>
Done.
> > ## Summary
> >
> > The aim of this RFC is to address the following list of problems
> > formulated at MRG planning meeting:
> > - protocol backward compatibility to enable cluster upgrade w/o
> > downtime
> > - consistency of data on replica and leader
> > - switch from leader to replica without data loss
> > - up to date replicas to run read-only requests
> > - ability to switch async replicas into sync ones
>
> 2. Ability to switch async replicas into sync ones and vice-versa? Or not?
>
Both ways, updated.
> > - guarantee of rollback on leader and sync replicas
> > - simplicity of cluster orchestration
> >
> > What this RFC is not:
> >
> > - high availability (HA) solution with automated failover, roles
> > assignments an so on
> > - master-master configuration support
> >
> >
> > ## Background and motivation
> >
> > There are number of known implemenatation of consistent data presence in
> > a cluster. They can be commonly named as "wait for LSN" technique. The
> > biggest issue with this technique is the abscence of rollback gauarantees
>
> 3. typo: gauarantees -> guarantees
>
done
> > at replica in case of transaction failure on one master or some of the
> > replics in the cluster.
>
> 4. typo: replics -> replicas
> >
done
> > To provide such capabilities a new functionality should be introduced in
> > Tarantool core, with limitation mentioned before - backward compatilibity
> > and ease of cluster orchestration.
>
> 5. but there is nothing mentioned before about these limitations.
>
They were named as problems to address, so I renamed them as
requirements.
[cut]
Pushed updated version to the branch.
Thanks,
Sergos
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