[Gluster-devel] semi-sync replication

[Aravinda]

I think NSR is good candidate here. It has leadership election for 
writing data, if that can be enhanced to give more priority to SSD 
bricks during leadership election.

regards
Aravinda

On 08/12/2015 06:06 PM, Ravishankar N wrote:
>
>
> 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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>
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