Migrating Cassandra to New Nodes

[nash <na...@gmail.com>]

I have a new set of nodes and I'd like to migrate my entire cluster onto
them without any downtime. I believe that I can launch the new cluster and
have them join the ring and then use nodetool to decommission the old nodes
one at a time. But, I'm wondering what is the safest way to update the
seeds in the cassandra.yaml files? AFAICT, there is nothing particularly
special about the choices of seeds? So, prior to starting decom, I was
figuring I could update all the seeds to some subset of the new cluster. Is
that reliable?

TIA,

--nash

Re: Migrating Cassandra to New Nodes

[Robert Coli <rc...@eventbrite.com>]

On Mon, Apr 28, 2014 at 10:52 PM, nash <na...@gmail.com> wrote:

> I have a new set of nodes and I'd like to migrate my entire cluster onto
> them without any downtime. I believe that I can launch the new cluster and
> have them join the ring and then use nodetool to decommission the old nodes
> one at a time. But, I'm wondering what is the safest way to update the
> seeds in the cassandra.yaml files? AFAICT, there is nothing particularly
> special about the choices of seeds? So, prior to starting decom, I was
> figuring I could update all the seeds to some subset of the new cluster. Is
> that reliable?
>

The fastest way to vertically scale a node is :

https://engineering.eventbrite.com/changing-the-ip-address-of-a-cassandra-node-with-auto_bootstrapfalse/

As a minor note, you do lose any hints destined for that node while you are
doing the copy, so use pre-copy techniques (rsync, then re-rsync with
--delete) and then immediately repair to shorten the window of
inconsistency if you read at CL.ONE.

=Rob

RE: Migrating Cassandra to New Nodes

[Arindam Barua <ab...@247-inc.com>]

What you have described below should work just fine.
When I was replacing nodes in my ring, I ended up creating a new datacenter with the new nodes, but I was upgrading to vnodes too at the time.

-Arindam

From: nash [mailto:nashef@gmail.com]
Sent: Monday, April 28, 2014 10:52 PM
To: user@cassandra.apache.org
Subject: Migrating Cassandra to New Nodes

I have a new set of nodes and I'd like to migrate my entire cluster onto them without any downtime. I believe that I can launch the new cluster and have them join the ring and then use nodetool to decommission the old nodes one at a time. But, I'm wondering what is the safest way to update the seeds in the cassandra.yaml files? AFAICT, there is nothing particularly special about the choices of seeds? So, prior to starting decom, I was figuring I could update all the seeds to some subset of the new cluster. Is that reliable?

TIA,

--nash