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From aaron morton <aa...@thelastpickle.com>
Subject Re: Uneven distribution using RP
Date Mon, 21 Jun 2010 10:44:48 GMT
According to http://wiki.apache.org/cassandra/Operations nodetool repair is used to perform
a major compaction and compare data between the nodes, repairing any conflicts. Not sure that
would improve the load balance, though it may reduce some wasted space on the nodes.

nodetool loadbalance will remove the node from the ring after streaming it's data to the remaining
nodes and the add it back in the busiest part. I've used it before and it seems to do the
trick. 

Also consider the size of the rows. Are they generally similar or do you have some that are
much bigger? The keys will be distributed without considering the size of the data. 

The RP is random though, i do not think it tries to evenly distribute the keys. So some variance
with a small number of nodes should be expected IMHO.

Aaron

On 21 Jun 2010, at 02:31, James Golick wrote:

> I ran cleanup on all of them and the distribution looked roughly even after that, but
a couple of days later, it's looking pretty uneven.
> 
> On Sun, Jun 20, 2010 at 10:21 AM, Jordan Pittier - Rezel <jordan@rezel.net> wrote:
> Hi,
> Have you tried nodetool repair (or cleanup) on your nodes ?
> 
> 
> On Sun, Jun 20, 2010 at 4:16 PM, James Golick <jamesgolick@gmail.com> wrote:
> I just increased my cluster from 2 to 4 nodes, and RF=2 to RF=3, using RP.
> 
> The tokens seem pretty even on the ring, but two of the nodes are far more heavily loaded
than the others. I understand that there are a variety of possible reasons for this, but I'm
wondering whether anybody has suggestions for now to tweak the tokens such that this problem
is alleviated. Would it be better to just add 2 more nodes?
> 
> Address       Status     Load          Range                                      Ring
>                                        170141183460469231731687303715884105728
> 10.36.99.140  Up         61.73 GB      43733172796241720623128947447312912170     |<--|
> 10.36.99.134  Up         69.7 GB       85070591730234615865843651857942052864     | 
 |
> 10.36.99.138  Up         54.08 GB      128813844387867495544257452469445200073    | 
 |
> 10.36.99.136  Up         54.75 GB      170141183460469231731687303715884105728    |-->|
>  
> 
> 


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