[ https://issues.apache.org/jira/browse/CASSANDRA-4658?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Sylvain Lebresne updated CASSANDRA-4658: ---------------------------------------- Fix Version/s: (was: 1.2.2) 1.2.3 > Explore improved vnode-aware replication strategy > ------------------------------------------------- > > Key: CASSANDRA-4658 > URL: https://issues.apache.org/jira/browse/CASSANDRA-4658 > Project: Cassandra > Issue Type: Bug > Affects Versions: 1.2.0 beta 1 > Reporter: Nick Bailey > Fix For: 1.2.3 > > > It doesn't look like the current vnode placement strategy will work with > people using NTS and multiple racks. > For reasons also described on CASSANDRA-3810, using racks and NTS requires > tokens to alternate racks around the ring in order to get an even > distribution of data. The current solution for upgrading/placing vnodes won't > take this into account and will likely generate some hotspots around the > ring. > Not sure what the best solution is. The two immediately obvious approaches > appear to be quite complicated at first. > * Fixing NTS to remove the requirement for rack ordering > ** No idea how this would be accomplished > ** Presents challenges for people upgrading. Would need to deprecate NTS for > a new strategy that replaces it, then have a clear upgrade path to that > strategy which would need to be in a pre 1.2 release. > * Changing vnode placement strategy > ** Ordering vnodes would require quite a bit of additional logic. Adding a > new node or rack would also need to maintain ordering which could cause > enough data movement to remove any benefits vnodes have already. > ** We could potentially adjust vnode token placement to offset any imbalances > caused by NTS but this would require a fairly intelligent mechanism for > determining vnode placement. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira