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From Mark Reddy <mark.re...@boxever.com>
Subject Re: Migrating to new datacenter
Date Mon, 07 Apr 2014 16:45:57 GMT
I would go with option 1.

I think it is the safer of the two options, involves less work and if
something were to go wrong mid migration you can remove the second DC from
your keyspace replication and have a clean break. SimpleStrategy will work
across DCs. It is generally advised to not use it across DCs as it is hard
to maintain and can induce latency on writes depending on DC distance,
however as you are just migrating and then killing the original DC you
won't face these issues.


Mark


On Mon, Apr 7, 2014 at 5:25 PM, Brandon McCauslin <bm3780@gmail.com> wrote:

> We're currently running a small 5 node 2.0.5 cluster in a single
> datacenter using the SimpleStrategy replication strategy with replication
> factor of 3.  We want to migrate our data from our current datacenter to a
> new datacenter, without incurring any downtime or data loss.  There is no
> plan to maintain or keep the old (current) datacenter after the migration
> is complete.  I'm wondering how best to go about this migration.
>
> *Shoud We:*
>
>    1. add a 2nd datacenter as described here - "Adding a datacenter to
>    cluster<http://www.datastax.com/documentation/cassandra/2.0/cassandra/operations/ops_add_dc_to_cluster_t.html>",
>    then decommission the 1st datacenter<http://www.datastax.com/documentation/cassandra/2.0/cassandra/operations/ops_decomission_dc_t.html>.
>     Can we even do this given we're currently setup with SimpleStrategy
>    replication?
>    2. or should we just start adding new nodes from the new datacenter to
>    our existing cluster as described here<http://www.datastax.com/documentation/cassandra/2.0/cassandra/operations/ops_add_node_to_cluster_t.html>?
>     Then once we've added all the new nodes, start decommissioning all the old
>    nodes from the old/current datacenter as described here<http://www.datastax.com/documentation/cassandra/2.0/cassandra/operations/ops_remove_node_t.html>
>    .
>
> Thanks for your help and time!
>

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