Thanks for the confirmation on the approach. The new dc is not yet ready,
but while I'm waiting I was thinking about updating the existing dc's
replication strategy from "SimpleStrategy" to "NetworkTopologyStrategy". I
also assume I'll need to update my snitch from the current SimpleSnitch to
PropertyFileSnitch. Here's the steps I'm thinking:
1. update snitch from SimpleSnitch to PropertyFileSnitch
- edit/create cassandra-topology.properties to enumerate all nodes
in current dc
- change snitch in cassandra.yaml on all nodes
- restart all nodes??
- run full repair on keyspace
2. update replication from "SimpleStrategy" to "NetworkTopologyStrategy"
a. ALTER KEYSPACE cfs
WITH REPLICATION = {'class' : 'NetworkTopologyStrategy', 'dc1'
: 3};
b. nodetool repair cfs
Let me know if anything here sounds wrong. Thanks!
would like to start preparing the existing datacenter
wondering if I could start updating the existing datacenter's replication
staconfiguration
On Mon, Apr 7, 2014 at 12:45 PM, Mark Reddy <[email protected]> wrote:
> 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 <[email protected]>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!
>>
>
>
