Check "nodetool info" on each node to get its rack and DC, and put that information in *cassandra-rackdc.properties *(even if you have no rack defined, the nodes are assigned to a default rack and you'll want to use the same). Then as you said, change the snitch in the yaml and restart the node. If you want to play it safe, check "nodetool status" on other nodes in the cluster after each restart so that you can verify it's still located where it should be.
Once you've applied the new snitch everywhere delete or rename *cassandra-topology.properties* to avoid having it used again if there's an accidental rollback in the yaml. On Wed, Feb 27, 2019 at 1:32 PM shalom sagges <shalomsag...@gmail.com> wrote: > Thanks for the info Alex! > > I read > https://docs.datastax.com/en/cassandra/3.0/cassandra/operations/opsSwitchSnitch.html > but still have a few questions: > > Our clusters are comprised of 2 DCs with no rack configuration, RF=3 on > each DC. > In this scenario, if I wish to seamlessly change the snitch with 0 > downtime, do I need to add the cassandra-rackdc.properties file, change the > snitch in cassandra.yaml and restart one by one? > Will this method cause problems? > > Thanks! > > > On Wed, Feb 27, 2019 at 12:18 PM Alexander Dejanovski < > a...@thelastpickle.com> wrote: > >> You'll be fine with the SimpleSnitch (which shouldn't be used either >> because it doesn't allow a cluster to use multiple datacenters or racks). >> Just change the IP and upon restart the node will redeclare itself in the >> ring. If your node is a seed node, you'll need to update your seed list >> across the cluster. >> >> On Wed, Feb 27, 2019 at 10:52 AM wxn...@zjqunshuo.com < >> wxn...@zjqunshuo.com> wrote: >> >>> I'm using SimpleSnitch. I have only one DC. Is there any problem to >>> follow the below procedure? >>> >>> -Simon >>> >>> *From:* Alexander Dejanovski <a...@thelastpickle.com> >>> *Date:* 2019-02-27 16:07 >>> *To:* user <user@cassandra.apache.org> >>> *Subject:* Re: Question on changing node IP address >>> >>> I confirm what Oleksandr said. >>> Just stop Cassandra, change the IP, and restart Cassandra. >>> If you're using the GossipingPropertyFileSnitch, the node will redeclare >>> its new IP through Gossip and that's it. >>> If you're using the PropertyFileSnitch, well... you shouldn't as it's a >>> rather dangerous and tedious snitch to use. But if you are, it'll require >>> to change the file containing all the IP addresses across the cluster. >>> >>> I've been changing IPs on a whole cluster back in 2.1 this way and it >>> went through seamlessly. >>> >>> Cheers, >>> >>> On Wed, Feb 27, 2019 at 8:54 AM Oleksandr Shulgin < >>> oleksandr.shul...@zalando.de> wrote: >>> >>>> On Wed, Feb 27, 2019 at 4:15 AM wxn...@zjqunshuo.com < >>>> wxn...@zjqunshuo.com> wrote: >>>> >>>>> >After restart with the new address the server will notice it and log >>>>> a warning, but it will keep token ownership as long as it keeps the old >>>>> host id (meaning it must use the same data directory as before restart). >>>>> >>>>> Based on my understanding, token range is binded to host id. As long >>>>> as host id doesn't change, everything is ok. Besides data directory, any >>>>> other thing can lead to host id change? And how host id is caculated? For >>>>> example, if I upgrade Cassandra binary to a new version, after restart, >>>>> will host id change? >>>>> >>>> >>>> I believe host id is calculated once the new node is initialized and >>>> never changes afterwards, even through major upgrades. It is stored in >>>> system keyspace in data directory, and is stable across restarts. >>>> >>>> -- >>>> Alex >>>> >>>> -- >>> ----------------- >>> Alexander Dejanovski >>> France >>> @alexanderdeja >>> >>> Consultant >>> Apache Cassandra Consulting >>> http://www.thelastpickle.com >>> >>> -- >> ----------------- >> Alexander Dejanovski >> France >> @alexanderdeja >> >> Consultant >> Apache Cassandra Consulting >> http://www.thelastpickle.com >> > -- ----------------- Alexander Dejanovski France @alexanderdeja Consultant Apache Cassandra Consulting http://www.thelastpickle.com
