Oh, if you're adding the same hosts to another cluster then the old cluster might try to communicate to the decommissioned nodes if you do that before the 3 day grace period. The cluster name not matching is a good protection, otherwise the two clusters will connect to each other and mayhem will ensue. You definitely don't want this to happen!
Unfortunately this delay of 3 days is hard-coded and non-configurable before 4.0 (see https://issues.apache.org/jira/browse/CASSANDRA-15596). As long as all the old cluster nodes are UP and don't see the decommissioned node on "nodetool status", you can safely assassinate decommissioned nodes to prevent this. The requirement that all nodes in the cluster are UP before safely assassinating a node is to prevent a down node from trying to connect to the decommissioned node after it recovers. Em qui., 17 de set. de 2020 às 17:25, Krish Donald <gotomyp...@gmail.com> escreveu: > Thanks Paulo, > > We have to decommission multiple nodes from the cluster and move those > nodes to other clusters. > So if we have to wait for 3 days for every node then it is going to take a > lot of time. > If i am trying to add the decommissioned node to the other cluster it is > giving me an error that cluster_name is not matching however cluster name > is correct as per new cluster. > So until i issue assasinate , i am not able to move forward. > > On Thu, Sep 17, 2020 at 1:13 PM Paulo Motta <pauloricard...@gmail.com> > wrote: > >> After decommissioning the node remains in gossip for a period of 3 days >> (if I recall correctly) and it will show up on describecluster during that >> period, so this is expected behavior. This allows other nodes that >> eventually were down when the node decommissioned to learn that this node >> left the cluster. >> >> What assassinate does is remove the node from gossip, so that's why it no >> longer shows up on describecluster, but this shouldn't be necessary. You >> should check that the node successfully decommissioned if it doesn't show >> up on "nodetool status". >> >> Em qui., 17 de set. de 2020 às 14:26, Krish Donald <gotomyp...@gmail.com> >> escreveu: >> >>> We are on 3.11.5 opensource cassandra >>> >>> On Thu, Sep 17, 2020 at 10:25 AM Krish Donald <gotomyp...@gmail.com> >>> wrote: >>> >>>> Hi, >>>> >>>> We decommissioned a node from the cluster. >>>> On decommissioned node it said in system.log that node has been >>>> decommissioned . >>>> But after couple of minutes only , on rest of the nodes the node is >>>> showing UNREACHABLE when we issue nodetool describecluster . >>>> >>>> nodetool status is not showing the node however nodetool >>>> describecluster is showing UNREACHABLE. >>>> >>>> I tried nodetool assassinate and now node is not showing in nodetool >>>> describecluster , however that seems to be the last option. >>>> >>>> Ideally it should leave the cluster immediately after decommission. >>>> Once decommissioned is completed as per log then is there any issue in >>>> issuing nodetool assasinate ? >>>> >>>> Thanks >>>> >>>>
