Large ring_creation_size

Anthony Molinaro anthonym at alumni.caltech.edu
Wed Apr 13 15:53:05 EDT 2011


My understanding is that it's not riak which ultimately limits the size of the
cluster but erlang distribution protocol.  By default erlang nodes are fully
connected, so if you have 1000 nodes you have about 999 outgoing connections
from each node, and with the net tick, they start to receive a lot of chatter.

I believe that scalaris may be engineered for larger growth by not using erlang
distribution protocol but their own, and only have a few outgoing connections
per node.

I'm also interested in what basho has to say.

-Anthony

On Wed, Apr 13, 2011 at 12:41:09PM -0700, Greg Nelson wrote:
> The largest known riak cluster != the largest possible riak cluster. ;-)
> 
> The inter node communication of the cluster depends on the data set and usage pattern, doesn't it? Or is there some constant overhead that tops out at a few hundred nodes? I should point out that we'll have big data, but not a huge number of keys.
> 
> The number of vnodes in the cluster should be equal to the ring_creation_size under normal circumstances, shouldn't it? So when I have a one node cluster, that node is running ring_creation_size vnodes... File descriptors probably isn't a problem -- these machines won't be doing anything else, and the limits are set to 65536.
> 
> Thinking about the internode communication you mentioned, that's probably where the resource hog is.. socket buffers, etc.
> 
> Anyway, I'd also love to hear more from basho. :)
> On Wednesday, April 13, 2011 at 12:33 PM, siculars at gmail.com wrote: 
> > Ill just chime in and say that this is not practical for a few reasons. The largest known riak cluster has like 50 or 60 nodes. Afaik, inter node communication of erlang clusters top out at a few hundred nodes. I'm also under the impression that each physical node has to have enough file descriptors to accommodate every virtual node in the cluster. 
> > 
> > I'd love to hear more from basho. 
> > 
> > -alexander 
> > 
> > 
> > Sent from my Verizon Wireless BlackBerry
> > 
> > -----Original Message-----
> > From: Greg Nelson <grourk at dropcam.com>
> > Sender: riak-users-bounces at lists.basho.com
> > Date: Wed, 13 Apr 2011 12:13:34 
> > To: <riak-users at lists.basho.com>
> > Subject: Large ring_creation_size
> > 
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-- 
------------------------------------------------------------------------
Anthony Molinaro                           <anthonym at alumni.caltech.edu>




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