Merge Cassandra RACs?

[Ian Spence <Ia...@globalrelay.net>]

Environment: Cassandra: 2.2.9, JRE: 1.8.0_74, CentOS 6/7

We have two DCs. In DC1 we have 3 RACs and in DC2 we have 6.

Because we're in a physical environment (not virtual or cloud based), we've run
short on unique rack space in DC2 and need to fix the layout problems.

Is it possible to somehow merge Cassandra racks without having to decommission
the nodes and re-add them to the cluster one by one? Or is that the correct way to accomplish this?

Thanks

Re: Merge Cassandra RACs?

[Anup Shirolkar <an...@instaclustr.com>]

Hi,

The answer to your question on 'merge Cassandra racks' is, the only safe
way to migrate nodes across physical racks is to perform a DC migration.
This does not include decommissioning and re-adding nodes.
It should be done if the system is stable and do not have other issues.

Talking about unique rack situation, why have you run out of racks ?
Are you currently installing each node on a new rack at the moment ?

There could be simpler alternatives depending upon your rack/data centre
situation.

Regards,

Anup Shirolkar




On Fri, 26 Oct 2018 at 04:52, Ian Spence <Ia...@globalrelay.net> wrote:

> Environment: Cassandra: 2.2.9, JRE: 1.8.0_74, CentOS 6/7
>
> We have two DCs. In DC1 we have 3 RACs and in DC2 we have 6.
>
> Because we're in a physical environment (not virtual or cloud based),
> we've run
> short on unique rack space in DC2 and need to fix the layout problems.
>
> Is it possible to somehow merge Cassandra racks without having to
> decommission
> the nodes and re-add them to the cluster one by one? Or is that the
> correct way to accomplish this?
>
> Thanks
>
>