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From Aiman Parvaiz <>
Subject Re: Need advice for multi DC C* setup
Date Mon, 17 Aug 2015 19:12:57 GMT
Over the weekend and after some more looking around and following this old
mailing list post

I was able to get my 2 node test env to move to over 3 node RF 3 cluster in
private subnet VPC in region B. I updated the RF when I started replication
between C* in public subnet to private subnet in region B.

The catch here is that since the test env was 2 nodes and both nodes were
in one AZ changing snitch to EC2Multiregion didnt afftect the replica
placement and hence I was able to get away with a rolling restart  but in
production I have 10 nodes spread over 2 AZ running simple snitch. I wonder
what would be the best way to change snitch live in this scenario.

One way I think would be to get all nodes in one AZ and then switch the
snitch that way ec2multiregion would report all nodes in 1 Rack but I am
open to suggestions also if this is a valid concern.


On Sun, Aug 16, 2015 at 1:46 AM, Prem Yadav <> wrote:

> I meant the existing nodes must be in the default VPC if you did not
> create one,
> In any case, you can use the VPC peering.
> On Sun, Aug 16, 2015 at 5:34 AM, John Wong <> wrote:
>> > The EC2 nodes must be in the default VPC.
>> Did you really mean the default VPC created by AWS or just a VPC? Because
>> I would be very surprise default VPC must be used.
>> On Sat, Aug 15, 2015 at 2:50 AM, Prem Yadav <> wrote:
>>> The EC2 nodes must be in the default VPC.
>>> create a ring in the VPC in region B. Use VPC peering to connect the
>>> default and the region B VPC.
>>> The two rings should join the existing one. Alter the replication
>>> strategy to network replication so that the data is replicated to the new
>>> rings. Repair the keyspaces.
>>> Once it is done, you can decommission the existing ring.
>>> For spark,if you are using datastax version, it comes with spark. You
>>> just need to change a config and spark starts along with cassandra. A
>>> separate ring is advised for analytics stuff.
>>> On Sat, Aug 15, 2015 at 1:10 AM, Aiman Parvaiz <>
>>> wrote:
>>>> Hi all
>>>> We are planning to move C* from EC2 (region A) to VPC in region B. I
>>>> will enumerate our goals so that you guys can advice me keeping in mind the
>>>> bigger picture.
>>>> Goals:
>>>> - Move to VPC is another region.
>>>> - Enable Vnodes.
>>>> - Bump up RF to 3.
>>>> - Ability to have a spark cluster.
>>>> I know this is a LOT of work and I know this all might not be possible
>>>> in one go.
>>>> Existing cluster in EC2 is using RF=2, simple snitch and simple
>>>> replication.
>>>> I am not sure what would be the best way to approach this task. So
>>>> please anyone who has done this and would like to share anything I would
>>>> really appreciate the effort.
>>>> Thanks

*Aiman Parvaiz*
Lead Systems Architect
cell: 213-300-6377

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