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From Oleksandr Shulgin <oleksandr.shul...@zalando.de>
Subject Re: system_auth replication factor in Cassandra 2.1
Date Wed, 30 Aug 2017 16:19:35 GMT
On Wed, Aug 30, 2017 at 5:50 PM, Chuck Reynolds <creynolds@ancestry.com>
wrote:

> So I’ve read that if your using authentication in Cassandra 2.1 that your
> replication factor should match the number of nodes in your datacenter.
>
>
>
> *Is that true?*
>
>
>
> I have two datacenter cluster, 135 nodes in datacenter 1 & 227 nodes in an
> AWS datacenter.
>
>
>
> *Why do I want to replicate the system_auth table that many times?*
>
>
>
> *What are the benefits and disadvantages of matching the number of nodes
> as opposed to the standard replication factor of 3? *
>
>
>
>
>
> The reason I’m asking the question is because it seems like I’m getting a
> lot of authentication errors now and they seem to happen more under load.
>
>
>
> Also, querying the system_auth table from cqlsh to get the users seems to
> now timeout.
>

This is surprising.

How many users do you have (or expect to be found in system_auth.users)?
What are the current RF for system_auth and consistency level you are using
in cqlsh?  Did you try to obtain a trace of a timing-out query (with
TRACING ON)?

Regards,
-- 
Oleksandr "Alex" Shulgin | Database Engineer | Zalando SE | Tel: +49 176
127-59-707

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