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From Ryan Svihla>
Subject Re: Disconnecting two data centers
Date Wed, 08 Mar 2017 14:38:02 GMT
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 <>

> 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?


Ryan Svihla

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