Thanks for the reply, Aaron! On Tue, Apr 12, 2011 at 10:52 PM, aaron morton <aa...@thelastpickle.com> wrote: > Are you changing the replication factor or moving nodes ?
I am just changing the replication factor, without touching the node configuration. > > To change the RF you need to repair and then once all repairing is done run > cleanup to remove the hold data. Do I need to shutdown the cluster when running the repair? If I just repair the nodes one by one, will some users get the error of no data exists, if the node responsible for the new replica is not yet repaired? Yudong > > You can move whole nodes by moving all their data with them, assigning a new > ip, and updating the topology file if used. > > Aaron > > On 13 Apr 2011, at 07:56, Yudong Gao wrote: > >> Hi, >> >> What operations will be executed (and what is the associated overhead) >> when the Keyspace replication factor is changed online, in a >> multi-datacenter setup with NetworkTopologyStrategy? >> >> I checked the wiki and the archive of the mailing list and find this, >> but it is not very complete. >> >> http://wiki.apache.org/cassandra/Operations >> " >> Replication factor is not really intended to be changed in a live >> cluster either, but increasing it may be done if you (a) use >> ConsistencyLevel.QUORUM or ALL (depending on your existing replication >> factor) to make sure that a replica that actually has the data is >> consulted, (b) are willing to accept downtime while anti-entropy >> repair runs (see below), or (c) are willing to live with some clients >> potentially being told no data exists if they read from the new >> replica location(s) until repair is done. >> " >> >> More specifically, in this scenario: >> >> {DC1:1, DC2:1} -> {DC2:1, DC3:1} >> >> 1. Can this be done online without shutting down the cluster? I >> thought there is an "update keyspace" command in the cassandra-cli. >> >> 2. If so, what operations will be executed? Will new replicas be >> created in new locations (in DC3) and existing replicas be deleted in >> old locations (in DC1)? >> >> 3. Or they will be updated only with read with ConssitencyLevel.QUORUM >> or All, or "nodetool repair"? >> >> Thanks! >> >> Yudong > >
