Prerequisites

Date strings (and timestamps) are no longer accepted as valid timeuuid values. This change requires modifying queries that use these values. New methods have been added for working with timeuuid values. see Timeuuid functions in CQL data types.

DataStax Community 1.2.10 is not network-compatible with versions older than 1.0. If you want to perform a rolling restart, first upgrade the cluster to 1.0.x or 1.1.x, and then to 1.2.10, as described in the Cassandra 1.1 documentation. Data files from Cassandra 0.6 and later are compatible with Cassandra 1.2 and later. If it's practical to shut down cluster instead of performing a rolling restart, you can skip upgrading to an interim release and upgrade from Cassandra 0.6 or later to 1.2.3.

Do not upgrade if nodes in the cluster are down. The hints schema changed from 1.1 to 1.2.10. Cassandra automatically snapshots and then truncates the hints table as part of starting up 1.2.10 for the first time. Additionally, upgraded nodes will not store new hints destined for older (pre-1.2) nodes. Use the nodetool removetoken command to remove dead nodes.