Pradeep, Here are some related tickets that may also be helpful in understanding the current behavior of these options.
* https://issues.apache.org/jira/browse/CASSANDRA-5897 * https://issues.apache.org/jira/browse/CASSANDRA-9474 * https://issues.apache.org/jira/browse/CASSANDRA-10243 * https://issues.apache.org/jira/browse/CASSANDRA-10242 On Sun, Aug 26, 2018 at 1:20 PM, Joshua Galbraith <jgalbra...@newrelic.com> wrote: > Pradeep, > > That being said, I haven't experimented with -Dcassandra.ignore_dc=true > -Dcassandra.ignore_rack=true before. > > The description here may be helpful: > https://github.com/apache/cassandra/blob/trunk/NEWS.txt#L685-L693 > > I would spin up a small test cluster with data you don't care about and > verify that your above assumptions are correct there first. > > On Sun, Aug 26, 2018 at 1:09 PM, Joshua Galbraith <jgalbra...@newrelic.com > > wrote: > >> Pradeep. >> >> Right, so from that documentation is sounds like you actually have to >> stop all nodes in the cluster at once and bring them back up one at a time. >> A rolling restart won't work here. >> >> On Sun, Aug 26, 2018 at 11:46 AM, Pradeep Chhetri <prad...@stashaway.com> >> wrote: >> >>> 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/operati >>>> ons/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 >>>> >>> >>> >> >> >> -- >> *Joshua Galbraith *| Lead Software Engineer | New Relic >> > > > > -- > *Joshua Galbraith *| Lead Software Engineer | New Relic > -- *Joshua Galbraith *| Lead Software Engineer | New Relic
