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From Arvydas Jonusonis <arvydas.jonuso...@gmail.com>
Subject Re: Disconnecting two data centers
Date Wed, 08 Mar 2017 21:37:04 GMT
Do not change the cluster name - the cassandra service will not start on
the same sstables if the cluster name is changed.

Arvydas

On Wed, Mar 8, 2017 at 4:57 PM, Chuck Reynolds <creynolds@ancestry.com>
wrote:

> I was hoping I could do the following
>
> ·         Change seeds
>
> ·         Change the topology back to simply
>
> ·         Stop nodes in datacenter 2
>
> ·         Remove nodes in datacenter 2
>
> ·         Restart nodes in datacenter 2
>
>
>
> Somehow Cassandra holds on to the information about who was in the cluster.
>
>
>
> What if I also changed the cluster name in the Cassandra.yaml before
> restarting?
>
>
>
> Is the data bound to the cluster name?
>
>
>
> *From: *Ryan Svihla <rs@foundev.pro>
> *Reply-To: *"user@cassandra.apache.org" <user@cassandra.apache.org>
> *Date: *Wednesday, March 8, 2017 at 7:38 AM
> *To: *user <user@cassandra.apache.org>
> *Subject: *Re: Disconnecting two data centers
>
>
>
> it's a bit tricky and I don't advise it, but the typical pattern is (say
> you have DC1 and DC2):
>
>
>
> 1. partition the data centers from one another..kill the routing however
> you can (firewall, etc)
>
> 2. while partitioned log onto DC1 alter schema so that DC2 is not
> replicating), repeat for other.
>
> 2a. If using propertyfilesnitch remove the DC2 from all the DC1 property
> files and vice versa
>
> 2b. change the seeds setting in the cassandra.yaml accordingly (DC1 yaml's
> shouldn't have any seeds from DC2, etc)
>
> 3. rolling restart to account for this.
>
> 4,. run repair (not even sure how necessary this step is, but after doing
> RF changes I do this to prevent hiccups)
>
>
>
> I've done this a couple of times but really failing all of that, the more
> well supported and harder to mess up but more work approach is:
>
>
>
> 1. Set DC2 to RF 0
>
> 2. remove all nodes from DC2
>
> 3. change yamls for seed files (update property file if need be)
>
> 4. create new cluster in DC2,
>
> 5. use sstableloader to stream DC1 data to DC2.
>
>
>
> On Wed, Mar 8, 2017 at 8:13 AM, Chuck Reynolds <creynolds@ancestry.com>
> wrote:
>
> I’m running C* 2.1.13 and I have two rings that are replicating data from
> our data center to one in AWS.
>
>
>
> We would like to keep both of them for a while but we have a need to
> disconnect them.  How can this be done?
>
>
>
>
>
> --
>
> Thanks,
>
> Ryan Svihla
>

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