Thanks Magnus and Shaun, that's very helpful. Daniel
On Wed, Feb 8, 2017 at 4:00 AM, Magnus Kessler <mkess...@basho.com> wrote: > On 7 February 2017 at 23:25, Daniel Miller <dmil...@dimagi.com> wrote: > >> Hi Riak Users, >> >> In the documentation >> <http://docs.basho.com/riak/kv/2.2.0/using/admin/commands/#leave> for >> riak-admin >> cluster leave it says “You can stage multiple leave command before >> planning/committing.” This implies that it is safe to stage multiple nodes >> leaving the cluster simultaneously. Is that true? Will all data in the >> cluster be continuously available during the removal period if, for >> example, I setup and commit a plan for 3 nodes to be leave a 9-node cluster >> (assuming there is enough space for the data on the remaining 6 nodes)? >> >> I had asked a similar question on IRC a couple weeks ago. In that case I >> was asking about replacing multiple nodes simultaneously using riak-admin >> cluster replace. The answer I got there left some doubt in my mind as to >> whether it is safe (i.e., will not result in a period data availability) to >> have multiple nodes leaving the cluster at once. The documentation for >> replace implies that it is safe to replace multiple nodes simultaneously as >> well: “You can stage multiple replace actions before planning/committing.” >> >> Note that I am not asking about force-remove or force-replace, which I >> would expect to result in permanent data loss if multiple nodes are >> force-removed/replaced simultaneously. >> >> My cluster is running Riak 2.1.1 with standard nval of 3. >> >> Thanks! >> Daniel >> >> > > Hi Daniel, > > Yes, staging several riak-admin cluster leave steps before riak-admin > cluster commit is safe. The leaving nodes will perform an ownership > handoff of all their partitions to other nodes in the cluster before > shutting themselves down. While this is happening, these nodes remain in > the cluster as fully functional nodes. The same is true for riak-admin > cluster replace. > > The reason we recommend staging of multiple leave or join operations is > that this minimises reshuffling data throughout the cluster. Only set of > ownership handoffs needs to happen, whereas if you were to perform several > consecutive leave or join operations, on each commit a substantial amount > of handoffs throughout the cluster is needed. > > Kind Regards, > > Magnus > > > -- > Magnus Kessler > Client Services Engineer > Basho Technologies Limited > > Registered Office - 8 Lincoln’s Inn Fields London WC2A 3BP Reg 07970431 >
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