Active Anti Entropy Directory when AAE is disabled

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Active Anti Entropy Directory when AAE is disabled

Arun Rajagopalan
Hello Riak Users

Lets say I stop Active Anti-Entropy by disabling it. Will the node continue to populate the anti_entropy ? 

This is part of a thinking exercise in case you wonder why I would want to do that :)

Thanks
Arun

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Re: Active Anti Entropy Directory when AAE is disabled

Luke Bakken
Hi Arun -

I don't know the answer off the top of my head, but I suspect that
disabling AAE will leave that directory and the files in it untouched
afterward.

One way to find out would be to disable AAE and monitor the access
time of the files in the anti_entropy directory.

--
Luke Bakken
Engineer
[hidden email]

On Wed, Jan 18, 2017 at 11:49 AM, Arun Rajagopalan
<[hidden email]> wrote:

> Hello Riak Users
>
> Lets say I stop Active Anti-Entropy by disabling it. Will the node continue
> to populate the anti_entropy ?
>
> This is part of a thinking exercise in case you wonder why I would want to
> do that :)
>
> Thanks
> Arun
>
> _______________________________________________
> riak-users mailing list
> [hidden email]
> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
>

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Re: Active Anti Entropy Directory when AAE is disabled

Arun Rajagopalan
Thanks Luke. Sorry it took me some time to experiment ...

I am not sure what happens in a couple of scenarios. Maybe you can explain

Lets say I lose a node completely and want to replace it. Will the keys yet to be "anti-entropied" by that node be distributed correctly when I restore that node ?

Secondly restore multiple nodes from a backup, should I replace the anti-entropy directory also ?



Arun Rajagopalan
215-901-5989

On Wed, Jan 18, 2017 at 3:22 PM, Luke Bakken <[hidden email]> wrote:
Hi Arun -

I don't know the answer off the top of my head, but I suspect that
disabling AAE will leave that directory and the files in it untouched
afterward.

One way to find out would be to disable AAE and monitor the access
time of the files in the anti_entropy directory.

--
Luke Bakken
Engineer
[hidden email]

On Wed, Jan 18, 2017 at 11:49 AM, Arun Rajagopalan
<[hidden email]> wrote:
> Hello Riak Users
>
> Lets say I stop Active Anti-Entropy by disabling it. Will the node continue
> to populate the anti_entropy ?
>
> This is part of a thinking exercise in case you wonder why I would want to
> do that :)
>
> Thanks
> Arun
>
> _______________________________________________
> riak-users mailing list
> [hidden email]
> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
>


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Re: Active Anti Entropy Directory when AAE is disabled

Magnus Kessler
On 25 January 2017 at 21:09, Arun Rajagopalan <[hidden email]> wrote:
Thanks Luke. Sorry it took me some time to experiment ...

I am not sure what happens in a couple of scenarios. Maybe you can explain

Lets say I lose a node completely and want to replace it. Will the keys yet to be "anti-entropied" by that node be distributed correctly when I restore that node ?

Secondly restore multiple nodes from a backup, should I replace the anti-entropy directory also ?


Hi Arun,

You can consider AAE data as ephemeral; AAE trees will be recalculated automatically if missing, or if trees are encountered that are too old (which may happen if you turn AAE off for some time and then on again).

In a forced replacement scenario (after completely losing a node), the replacement node would first calculate its own set of AAE trees, which would essentially be an empty set. Subsequent AAE exchanges with other nodes will detect the differences and cause missing KV objects to be repaired.

For more information about AAE and partition repairs, please see the documentation [0][1].

Kind Regards,

Magnus

[1]: https://docs.basho.com/riak/kv/2.2.0/using/repair-recovery/repairs/#repairing-partitions

--
Magnus Kessler
Client Services Engineer
Basho Technologies Limited

Registered Office - 8 Lincoln’s Inn Fields London WC2A 3BP Reg 07970431

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