Pradeep, it sounds like what you're proposing counts as a topology change because you are changing the datacenter name and rack name.
Please refer to the documentation here about what to do in that situation: https://docs.datastax.com/en/cassandra/3.0/cassandra/operations/opsSwitchSnitch.html In particular: Simply altering the snitch and replication to move some nodes to a new > datacenter will result in data being replicated incorrectly. Topology changes may occur when the replicas are placed in different places > by the new snitch. Specifically, the replication strategy places the > replicas based on the information provided by the new snitch. If the topology of the network has changed, but no datacenters are added: > a. Shut down all the nodes, then restart them. > b. Run a sequential repair and nodetool cleanup on each node. On Sun, Aug 26, 2018 at 11:14 AM, Pradeep Chhetri <prad...@stashaway.com> wrote: > Hello everyone, > > Since i didn't hear from anyone, just want to describe my question again: > > Am i correct in understanding that i need to do following steps to migrate > data from SimpleSnitch to GPFS changing datacenter name and rack name to > AWS region and Availability zone respectively > > 1) Update the rack and datacenter fields in cassandra-rackdc.properties > file and rolling restart cassandra with this flag > "-Dcassandra.ignore_dc=true -Dcassandra.ignore_rack=true" > > 2) Run nodetool repair --sequential and nodetool cleanup. > > 3) Rolling restart cassandra removing the flag "-Dcassandra.ignore_dc=true > -Dcassandra.ignore_rack=true" > > Regards, > Pradeep > > On Thu, Aug 23, 2018 at 10:53 PM, Pradeep Chhetri <prad...@stashaway.com> > wrote: > >> Hello, >> >> I am currently running a 3.11.2 cluster in SimpleSnitch hence the >> datacenter is datacenter1 and rack is rack1 for all nodes on AWS. I want to >> switch to GPFS by changing the rack name to the availability-zone name and >> datacenter name to region name. >> >> When I try to restart individual nodes by changing those values, it >> failed to start throwing the error about dc and rack name mismatch but >> gives me an option to set ignore_dc and ignore_rack to true to bypass it. >> >> I am not sure if it is safe to set those two flags to true and if there >> is any drawback now or in future when i add a new datacenter to the >> cluster. I went through the documentation on Switching Snitches but didn't >> get much explanation. >> >> Regards, >> Pradeep >> >> >> >> >> >> >> >> > -- *Joshua Galbraith *| Lead Software Engineer | New Relic
