Quick and dirty rebalancing of Cassandra cluster.

rebalance.sh

#!/bin/sh

# This will allow you to rebalance the Cassandra ring
#
# $ ./rebalance.sh file_of_hosts

RING_SIZE=$(echo "2^127" | bc)
HOSTS=$(cat $1 | sed 'N;s/\n/ /')
HOST_NUM=$(echo $HOSTS | wc -w)
INDEX=0

for host in $HOSTS
do
    token=$(echo "$INDEX*$RING_SIZE/$HOST_NUM" | bc)
    echo "Moving $host to $token"
    ssh $host "sudo nodetool -v -h localhost move $token"
    INDEX=$((INDEX+1))
done