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From Peter Fales <>
Subject Re: Data Center Move
Date Thu, 02 Sep 2010 18:28:15 GMT

I'm just getting my feet wet with Cassandra, so I'm far from an
expert, but I'm curious whether you saw my posting a few days ago
about using the EC2 "public" IP addreses with cassandra:

*If* I understand the problem correctly, it seems like you could create
some new EC2 nodes using this patched version of the code, then 
migrate your existing nodes to new EC2 nodes, but giving each new node a 
public IP.   Once your entire EC2 cluster was up and running on the
public addresses, you should be able to use those public addresses 
to migrate to some other site outside of EC2.  

Am I missing something obvious?   (Quite possible, since I haven't actually
tested this)

On Thu, Sep 02, 2010 at 01:09:46PM -0500, Anthony Molinaro wrote:
> Hi,
>   We're running cassandra 0.6.4, and need to do a data center move of
> a cluster (from EC2 to our own data center).   Because of the way the
> networks are set up we can't actually connect these boxes directly, so
> the original plan of add some nodes in the new colo, let them bootstrap
> then decommission nodes in the old colo until the data is all transfered
> will not work.
> So I'm wondering if the following will work
> 1. take a snapshot on the source cluster
> 2. rsync all the files from the old machines to the new machines (we'd most
>    likely be reducing the total number of machines, so would do things like
>    take 4-5 machines worth of data and put it onto 1 machine)
> 3. bring up the new machines in the new colo
> 4. run cleanup on all new nodes?
> 5. run repair on all new nodes?
> So will this work?  If so, are steps 4 and 5 correct?
> I realize we will miss any new data that happens between the snapshot
> and turning on writes on the new cluster, but I think we might be able
> to just tune compaction such that it doesn't happen, then just sync
> the files that change while the data transfers happen?
> Thanks,
> -Anthony
> -- 
> ------------------------------------------------------------------------
> Anthony Molinaro                           <>

Peter Fales
Member of Technical Staff
1960 Lucent Lane
Room: 9H-505
Naperville, IL 60566-7033
Phone: 630 979 8031

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