Hi Joshua, Thank you for the reply. Sorry i forgot to mention that I already went through that documentation. There are few missing things regarding which I have few questions:
1) One thing which isn't mentioned there is that cassandra fails to restart when we change the datacenter name *or* rack name of a node. So whether should i first rolling restart cassandra with flag "-Dcassandra.ignore_dc=true -Dcassandra.ignore_rack=true", then run sequential repair and then cleanup and then rolling restart cassandra without that flag. 2) Should i not allow any read/write operation from applications during the time when sequential repair is running. Regards, Pradeep On Mon, Aug 27, 2018 at 12:19 AM, Joshua Galbraith < jgalbra...@newrelic.com.invalid> wrote: > 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 >
