Eric,
Jonathan is suggesting the approach Jeremiah was using.
Calculate the tokens the nodes in each DC independantly, and then add 1
to the tokens if there are two nodes with the same tokens.
In your case with 2 DC's with 2 nodes each.
In DC 1
node 1 = 0
node 2 = 85070591730234615865843651857942052864
In DC 2
node 1 = 1
node 2 = 85070591730234615865843651857942052865
This will evenly distribute the keys in each DC, which is what the
NetworkTopologyStrategy is trying to do.
You can make this change using nodetool move.
Hope that helps.
-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com
On 4 May 2011, at 08:20, Eric tamme wrote:
> On Tue, May 3, 2011 at 4:08 PM, Jonathan Ellis <jbel...@gmail.com> wrote:
>> On Tue, May 3, 2011 at 2:46 PM, aaron morton <aa...@thelastpickle.com> wrote:
>>> Jonathan,
>>> I think you are saying each DC should have it's own (logical) token
>>> ring.
>>
>> Right. (Only with NTS, although you'd usually end up with a similar
>> effect if you alternate DC locations for nodes in a ONTS cluster.)
>>
>>> But currently two endpoints cannot have the same token regardless of
>>> the DC they are in.
>>
>> Also right.
>>
>>> Or should people just bump the tokens in extra DC's to avoid the collision?
>>
>> Yes.
>>
>
>
> I am sorry, but I do not understand fully. I would appreciate it if
> some one could explain with more verbosity for me.
>
> I do not understand why data insertion is even, but replication is not.
>
> I do not understand how to solve the problem. What does "bumping"
> tokens entail - Is that going to change my insertion distribution? I
> had no idea you can create different logical keyspaces ... and I am
> not sure what that exactly means... or that I even want to do it. Is
> there a clear solution to "fixing" the problem I laid out, and getting
> replication data evenly distributed between racks in each DC?
>
> Sorry again for needing more verbosity - I am learning as I go with
> this stuff. I appreciate everyones help.
>
> -Eric
