You didn't mention which version you're upgrading to, but generally you shouldn't add or remove nodes while the nodes your cluster is not all on on the same version. So if you're going to add nodes, you should do that before you upgrade the first node, or after you have upgraded all of them.
Shifting traffic away from DC1 may not be necessary, but shouldn't hurt. - EF _____________________________________ From: Timon Wong [timon86.w...@gmail.com] Sent: Saturday, August 6, 2016 02:03 To: user@cassandra.apache.org Subject: Doing rolling upgrades on two DCs Hello, newbie here. Currently we are using Cassandra v2.2.1 (two DCs, naming them DC1, DC2, respectively), and recently we have two issues: 1. Cannot adding new node due to CASSANDRA-10961 2. Cannot repair node, due to CASSANDRA-10501 We learned that we can do rolling upgrade, since we are only using one DC1 for now (DC2 is just for replica), we have following steps in mind: 1. Backup; 2. Doing upgrade on DC2. (Follows this guide: https://docs.datastax.com/en/latest-upgrade/upgrade/cassandra/upgrdCassandraDetails.html); 3. Do some checks (client compatibility, etc); 4. Adding nodes to DC2 (using new Cassandra); 5. Traffic our loads to DC2; 6. Upgrading DC1. Is that possible, or do we miss something? Thanks in advance! Timon
