Michael,
The answer to your first question is basically "yes".  The sysadmin really 
should be monitoring memory usage and disk space and adding nodes to the 
cluster when/if needed.  The SNMP hooks in the EnterpriseDS version are very 
handy for that type of thing and I'd be happy to have that conversation off 
list, if you're interested.  That being said, the system does automatically 
balance objects across the cluster evenly and adding a new node will trigger a 
re-balance that does not interrupt cluster function.  Currently, there is not 
really a way to force an un-even distribution across the cluster.

On the best-practices front, there is a section of the wiki that addresses 
exactly that at: https://wiki.basho.com/display/RIAK/Best+Practices

Beyond that, I'd add that Riak is generally happier with more nodes rather than 
fewer (e.g. If N=3, 5 nodes is a good place to start).

Best regards,
Dean

--
Dean Cookson
VP Business Development
Basho Technologies, Inc.
Google Voice: +1 415 692 1775
[email protected]


On Jul 12, 2010, at 2:59 PM, Michael Russo wrote:

> Hi all,
> 
> I'm currently evaluating Riak and am looking to understand the system in more 
> depth.  One of the best ways I know of doing this is to examine the edge 
> cases.  So, without further ado:
> 
> There are several per-node limitations that, if hit, could cause a Riak node 
> to stop functioning properly.  For example,
> 
> - disk: each node has a file system of finite size and cannot indefinitely 
> accept writes
> - memory: the Bitcask keydir structure must fit entirely in memory and thus 
> cannot indefinitely accept writes
> 
> From a management perspective, is the onus on the sysadmin to monitor disk 
> and memory usage and to increase the number of nodes in the cluster as 
> appropriate, or are there any built-in mechanisms to automatically re-balance 
> data across the cluster?  
> 
> Furthermore, if a limit is inadvertently hit, is there a re-balancing 
> mechanism available that can be manually triggered to compensate, or is it a 
> requirement that every node take an equal share of partitions?
> 
> Are there any other related best-practices?
> 
> Thanks,
> Michael
> _______________________________________________
> riak-users mailing list
> [email protected]
> http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com


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