Understanding RIAK Vnodes.

[viren...@teliax.com]

I'm super confused after reading Vnodes the more I read the more feel I understand less of Riak.

Assuming there are 3 nodes,  N=3 named  A, B and C. Ring Size: 64.

Which means the Vnode are  distributed between A, B and C as 21, 21 and 22 respectively

My Question is when a write is performed by RIAK does the write is written evenly in each node.

In other words

When PW=3, does that ensure that a copy of the data is written to each Vnode of A, B and C. 

Or

It can happen that a single node can have multiple copies of data in more than 1 vnode.(Ignoring the Sloppy quorum assumption over here)

[Bryan Hunt]

Viren, 

Yes, particularly in older versions of Riak the placement algorithm was an issue, particularly on small clusters, the vnode spread could be unsafe.

Take a look at this document, it explains the issue very well, and the work undertaken by Ramen Sen/Russell Brown to improve the situation: 

https://github.com/basho/riak_core/blob/develop-2.2/docs/claim-fixes.md

Bryan