I don't know exactly what your load is like, but I think the best w= ay to accomplish it is like this:
You have nodes: 1 2 3 4 5 6 7 8 9
A= dd SSD nodes: S1 1 2 3 S2 4 5 6 S3 7 8 9
Decommission 1, 4, 7
Check i= f you can remove more nodes
Decommission 2, 5, 8
Check if you can remove more nodes
Decommission = 3, 6, 9
And when you've stopped, make sure your ring is balanced by = using nodetool move.

It's probably a bad idea to run with a lops= ided cluster where some servers are much faster than the others. If you hav= e a replication factor of 3, that means that half of your data will be on t= wo slow and one fast machines (so quorum will be slow) and the oher half wi= ll be on two fast and one slow machine (so quorum will be fast). This leads= to the somewhat unintuitive conclusion that you can make the cluster go fa= ster by removing nodes.

But it's your data and your cluster, so you need to measure and ben= chmark and figure out what's best for you and your app.

/Hen= rik

On Mon, Aug 27, 2012 at 4:22 AM, Mohi= t Anchlia wrote:
use=A0nodetool decommission and nodetool rem= ovetoken

On Sun, Aug 26, 2012 at 5:31 PM, Senthilvel Rang= aswamy wrote:
We have a cluster of 9 nodes in the r= ing. We would like SSD backed boxes. But we may not need 9
nodes in that= case. What is the best way to downscale the cluster to 6 or 3 nodes.=

--
..Senthil

"If there's anything more important th= an my ego around, I want it
=A0caught and shot now."
=A0 =A0=A0= =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0=A0 - Douglas Adams.

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