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
