Cassandra multi datacenter, WAN hiccups and replication resiliency

Question

I have two DCs. My Cassandra ring spans both DCs. I use local quorum with replication factor=3. I do a write in DC1 with local quorum. Data gets written to multiple nodes in DC1. For the same write to propagate to DC2 only one copy is sent from the coordinator node in DC1 to a coordinator node in DC2 for optimizing traffic over the WAN (from what I have read in the Cassandra documentation)

Imagine there is a wan hiccup for a few seconds.

Questions about replication resiliency:

1. Will this Wan hiccup result in a Hinted Handoff (HH) being created in DC1's coordinator for DC2 to be delivered when the Wan link is up again?

2. I've read that HH only starts once the failure detector has recognized that a replica is unavailable. Will this hiccup of a few seconds cause some data to go undetected to DC2 till the next nodetool repair is run?

3. Is it advisable to run nodetool repairs in case of Wan hiccups that last a few seconds/minutes?

Answer 1

1. Yes

2. This is obsolete as of Cassandra 1.0, so no. (See http://www.datastax.com/dev/blog/whats-new-in-cassandra-1-0-windows-service-new-cql-clients-and-more)

3. As above, no.