> But I've read in some sources (for example > http://www.datastax.com/docs/1.0/initialize/cluster_init_multi_dc) that seed > list MUST include at least one seed from each DC and seed lists should be the > same for each node.
That article is about creating a new cluster, to add an a DC to an exiting cluster do this: * set the seed list in the new DC to have seeds from both DC's * update the seed list in the old DC to have seeds from both later. Adding a new DC will normally not happen as often as adding nodes. Using the GossipingPropertyFileSnitch means do you not not have to update all nodes when adding a new one. Cheers ----------------- Aaron Morton Freelance Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 17/05/2013, at 8:42 PM, Igor <i...@4friends.od.ua> wrote: > On 05/17/2013 11:19 AM, Sergey Naumov wrote: >> But I've read in some sources (for example >> http://www.datastax.com/docs/1.0/initialize/cluster_init_multi_dc) that seed >> list MUST include at least one seed from each DC and seed lists should be >> the same for each node. >> >> Or it is fine if nodes from new DC have all seeds specified and nodes from >> old DCs have all seeds specified except seeds from new DC? In such >> interpretation rules have to be a bit modified: > > I never have problems with adding new nodes and new DC having single seed per > cluster in one old DC. > >> 1. Nodes from the same DC should have identical seeds lists. >> 2. At least at one DC nodes MUST have in its seed lists seeds from all other >> DCs. >> >> >> 2013/5/17 Igor <i...@4friends.od.ua> >> I see no reason to restart all nodes. You can continue to use seed from >> first DC - seed used for loading ring configuration(locations, token ranges, >> etc), not data. >> >> On 05/17/2013 10:34 AM, Sergey Naumov wrote: >>> If I understand you correctly, GossipingPropertyFileSnitch is useful for >>> manipulations with nodes within a single DC, but to add a new DC without >>> having to restart every node in all DCs (because seeds are specified in >>> cassandra.yaml and I need to restart a node after addition of a new seed >>> from newly created DC), I anyway have to use cassandra-topology.properties >>> and edit it on every node of a cluster. >>> >>> By the way, it it necessary to specify seeds if I use PropertyFileSnitch >>> and there is info in cassandra-topology.properties about all nodes of a >>> cluster? >>> >> >> Yes, it is. Cassandra need seed(s), because topology properties have no info >> about token ranges. >> >> >>> >>> 2013/5/17 aaron morton <aa...@thelastpickle.com> >>> You should configure the seeds as recommended regardless of the snitch used. >>> >>> You need to update the yaml file to start using the >>> GossipingPropertyFileSnitch but after that it reads the >>> cassandra-rackdc.properties file to get information about the node. It >>> reads uses the information in gossip to get information about the other >>> nodes in the cluster. >>> >>> If there is no info in gossip about a remote node, because say it has not >>> been upgraded, it will fall back to using cassandra-topology.properties. >>> >>> Hope that helps. >>> >>> ----------------- >>> Aaron Morton >>> Freelance Cassandra Consultant >>> New Zealand >>> >>> @aaronmorton >>> http://www.thelastpickle.com >>> >>> On 15/05/2013, at 8:10 PM, Sergey Naumov <sknau...@gmail.com> wrote: >>> >>> > As far as I understand, GossipingPropertyFileSnitch supposed to provide >>> > more flexibility in nodes addition/removal. But what about addition of a >>> > DC? In datastax documentation >>> > (http://www.datastax.com/docs/1.2/operations/add_replace_nodes#add-dc) it >>> > is said that cassandra-topology.properties could be updated without >>> > restart for PropertyFileSnitch. But here >>> > (http://www.datastax.com/docs/1.0/initialize/cluster_init_multi_dc) it it >>> > said, that "you MUST include at least one node from EACH data center. It >>> > is a best practice to have at more than one seed node per data center and >>> > the seed list should be the same for each node". At the first glance it >>> > seems that PropertyFileSnitch will get necessary info from >>> > cassandra-topology.properties, but for GossipingPropertyFileSnitch >>> > modification of cassandra.yaml and restart of all nodes in all DCs will >>> > be required. Could somebody clarify this topic? >>> > >>> > Thanks in advance, >>> > Sergey Naumov. >>> >>> >> >> >
