This is a old post, am not sure if something changed for new C* versions. If nodetool compactionstats says there are no Validation compactions running (and the compaction queue is empty) and netstats says there is nothing streaming there is a a good chance the repair is finished or dead. If a neighbour dies during a repair the node it was started on will wait for 48 hours(?) until it times out. Check the logs on the machines for errors, particularly from the AntiEntropyService. And see what compactionstats is saying on all the nodes involved in the repair.
source: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Is-it-safe-to-stop-a-read-repair-and-any-suggestion-on-speeding-up-repairs-td6607367.html On Aug 1, 2014, at 2:46 AM, KZ Win <kz...@pelotoncycle.com> wrote: I have a 2 node apache cassandra (2.0.3) cluster with rep factor of 1. I change rep factor to 2 using the following command in cqlsh ALTER KEYSPACE "mykeyspace" WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 2 }; I then tried to run recommended "nodetool repair" after doing this type of alter. The problem is that this command sometimes finishes very quickly. When it does finishes like that it will normally say 'Lost notification...' and exit code is not zero. So I just repeat this 'nodetool repair' until it finishes without error. I also check that 'nodetool status' reports expected disk space for each node. (with rep factor 1, each node has say about 7GB each and I expect after nodetool repair that each is 14GB each assuming no cluster usage in the mean time) Is there a more correct way to determine that 'nodetool repair' is finished in this case?