incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Vijay <vijay2...@gmail.com>
Subject Re: Docs: Token Selection
Date Wed, 15 Jun 2011 18:14:45 GMT
Correction....

"The problem in the above approach is you have 2 nodes between 12 to 4 in
DC1 but from 4 to 12  you just have 1"

should be

"The problem in the above approach is you have 1 node between 0-4 (25%) and
and one node covering the rest which is 4-16, 0-0 (75%)"

Regards,
</VJ>



On Wed, Jun 15, 2011 at 11:10 AM, Vijay <vijay2win@gmail.com> wrote:

> The problem in the above approach is you have 2 nodes between 12 to 4 in
> DC1 but from 4 to 12  you just have 1.... (Which will cause uneven
> distribution of data the node)
> It is easier to think of the DCs as ring and split equally and interleave
> them together....
>
> DC1 Node 1 : token 0
> DC1 Node 2 : token 8..
>
> DC2 Node 1 : token 4..
> DC2 Node 1 : token 12..
>
> Regards,
> </VJ>
>
>
>
>
> On Tue, Jun 14, 2011 at 7:31 PM, AJ <aj@dude.podzone.net> wrote:
>
>>  Yes, which means that the ranges overlap each other.
>>
>> Is this just a convention, or is it technically required when using
>> NetworkTopologyStrategy?  Would it be acceptable to split the ranges into
>> quarters by ignoring the data centers, such as:
>>
>> DC1
>> node 1 = 0      Range: (12, 16], (0, 0]
>> node 2 = 4      Range: (0, 4]
>>
>> DC2
>> node 3 = 8      Range: (4, 8]
>> node 4 = 12   Range: (8, 12]
>>
>> If this is OK, are there any drawbacks to this?
>>
>>
>>
>> On 6/14/2011 6:10 PM, Vijay wrote:
>>
>> Yes... Thats right...  If you are trying to say the below...
>>
>>  DC1
>>  Node1 Owns 50%
>>
>>  (Ranges 8..4 -> 8..5 & 8..5 -> 0)
>>
>> Node2 Owns 50%
>>
>> (Ranges 0 -> 1 & 1 -> 8..4)
>>
>>
>>  DC2
>>  Node1 Owns 50%
>>
>>  (Ranges 8..5 -> 0 & 0 -> 1)
>>
>>   Node2 Owns 50%
>>
>>   (Ranges 1 -> 8..4 & 8..4 -> 8..5)
>>
>>
>>  Regards,
>> </VJ>
>>
>>
>>
>> On Tue, Jun 14, 2011 at 3:47 PM, AJ <aj@dude.podzone.net> wrote:
>>
>>> This http://wiki.apache.org/cassandra/Operations#Token_selection  says:
>>>
>>> "With NetworkTopologyStrategy, you should calculate the tokens the nodes
>>> in each DC independantly."
>>>
>>> and gives the example:
>>>
>>> DC1
>>> node 1 = 0
>>> node 2 = 85070591730234615865843651857942052864
>>>
>>> DC2
>>> node 3 = 1
>>> node 4 = 85070591730234615865843651857942052865
>>>
>>>
>>> So, according to the above, the token ranges would be (abbreviated nums):
>>>
>>> DC1
>>> node 1 = 0      Range: (8..4, 16], (0, 0]
>>> node 2 = 8..4   Range: (0, 8..4]
>>>
>>> DC2
>>> node 3 = 1      Range: (8..5, 16], (0, 1]
>>> node 4 = 8..5   Range: (1, 8..5]
>>>
>>>
>>> If the above is correct, then I would be surprised as this paragraph is
>>> the only place were one would discover this and may be easy to miss...
>>> unless there's a doc buried somewhere in plain view that I missed.
>>>
>>> So, have I interpreted this paragraph correctly?  Was this design to help
>>> keep data somewhat localized if that was important, such as a geographically
>>> dispersed DC?
>>>
>>> Thanks!
>>>
>>
>>
>>
>

Mime
View raw message