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From Scott Fines <>
Subject MapReduce with two ethernet cards
Date Mon, 10 Oct 2011 16:47:14 GMT
Hi all,

This may be a silly question, but I'm at a bit of a loss, and was hoping for some help.

I have a Cassandra cluster set up with two NICs--one for internel communication between cassandra
machines (10.1.1.*), and one to respond to Thrift RPC (172.28.*.*).

I also have a Hadoop cluster set up, which, for unrelated reasons, has to remain separate
from Cassandra, so I've written a little MapReduce job to copy data from Cassandra to Hadoop.
However, when I try to run my job, I get failed connecting to all endpoints,,

which is puzzling to me. It seems like the MR is attempting to connect to the internal communication
IPs instead of the external Thrift IPs. Since I set up a firewall to block external access
to the internal IPs of Cassandra, this is obviously going to fail.

So my question is: why does Cassandra MR seem to be grabbing the listen_address instead of
the Thrift one. Presuming it's not a funky configuration error or something on my part, is
that strictly necessary? All told, I'd prefer if it was connecting to the Thrift IPs, but
if it can't, should I open up port 7000 or port 9160 between Hadoop and Cassandra?

Thanks for your help,


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