[Gluster-devel] semi-sync replication

[Ravishankar N]

On 08/12/2015 05:56 PM, Anoop Nair wrote:
> Hmm, that's kind of risky. What if you good leg fails before the sync happens to the secondary leg?
Oh, the writes would still need to happen as a part of the AFR 
transaction; so if the writes (which are wound to all bricks 
immediately, its just that we don't wait for all responses before 
unwinding to DHT ) failed on some bricks, the self-heal would take care 
of it..

Thanks,
Ravi
>   Replay cache may serve as a lifeline in such a scenario.
>
> Thanks
> -Anoop
>
> ----- Original Message -----
> From: "Ravishankar N" <ravishankar at redhat.com>
> To: "Anoop Nair" <annair at redhat.com>, gluster-devel at gluster.org
> Sent: Wednesday, August 12, 2015 5:46:04 PM
> Subject: Re: [Gluster-devel] semi-sync replication
>
>
>
> On 08/12/2015 12:50 PM, Anoop Nair wrote:
>> Hi,
>>
>> Do we have plans to support "semi-synchronous" type replication in the future? By semi-sync I mean writing to one leg the replica, securing the write on a faster stable storage (capacitor backed SSD or NVRAM) and then acknowledge the client. The write on other replica leg may happen at later point in time.
> Not exactly in the way you describe, but there are plans to achieve
> "near-synchronous" replication wherein we wind the write to all replica
> legs, but acknowledge success as soon as we hear a success from one of
> the bricks (instead of waiting for responses from all bricks as we do
> today).
>
> -Ravi
>>    
>>
>> Thanks
>> -Anoop
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