Multiple nodes leaving cluster

Shaun McVey smcvey at basho.com
Wed Feb 8 03:50:44 EST 2017


Hi Daniel,

It should be safe, yes.  If you run the `cluster leave` commands, then run
`cluster plan` (but don't yet run `cluster commit`), the output will show
if there's any violations in spreading each of your 3 copies around the
cluster.  If it does provide a warning, you can `cluster clear` and backout
the changes.  If not, then you can `cluster commit` and the data will be
moved from the leaving nodes to the rest of the cluster.  Whether or not
you see any violations (i.e. more than one copy of data being stored on the
same physical server) will depend on a combination of number of nodes and
the ring size.

Shaun

On Tue, Feb 7, 2017 at 11:25 PM, Daniel Miller <dmiller at 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
>>
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