Hi Cassandra Folk,

We've experienced a problem a couple of times where Cassandra nodes lose a keyspace after a restart.  We've restarted 2 out of 3 nodes, and they have both experienced this problem; clearly we're doing something wrong, but don't know what.  The data files are all still there, as before, but the node can't see the keyspace (we only have one).  Tthe nodetool still says that each one is responsible for 33% of the keys, but the disk usage has dropped to a tiny amount on the nodes that we've restarted.  I saw this:

http://mail-archives.apache.org/mod_mbox/cassandra-user/201202.mbox/%3C4F3582E7.20907 <at> conga.com%3E

Seems to be exactly our problem, but we have not modified the cassandra.yaml - we have overwritten it through an automated process, and that happened just before restarting, but the contents did not change.

Any ideas as to what might cause this, or how the keyspace can be restored (like I say, the data is all still in the data directory).

We're running in AWS.

Thanks,

Conan