Thanks Aaron.  I'll make sure to copy the system tables.

Another thing -- do you have any suggestions on raid configurations for main data drives?  We're looking at RAID5 and 10 and I can't seem to find a convincing argument one way or the other.

Thanks again for your help.

On Mon, Jun 6, 2011 at 5:45 AM, aaron morton <> wrote:
Sounds like you are OK to turn off the existing cluster first.

Assuming so, deliver any hints using JMX then do a nodetool flush to write out all the memtables and checkpoint the commit logs. You can then copy the data directories.

The System data directory contains the nodes token and the schema, you will want to copy this directory. You may also want to copy the cassandra.yaml or create new ones with the correct initial tokens.

The nodes will sort themselves out when they start up and get new IP's, the important thing to them is the token.


Aaron Morton
Freelance Cassandra Developer

On 6 Jun 2011, at 23:25, Eric Czech wrote:

> Hi, I have a quick question about migrating a cluster.
> We have a cassandra cluster with 10 nodes that we'd like to move to a new DC and what I was hoping to do is just copy the SSTables for each node to a corresponding node in the new DC (the new cluster will also have 10 nodes).  Is there any reason that a straight file copy like this wouldn't work?  Do any system tables need to be moved as well or is there anything else that needs to be done?
> Thanks!