Re: Understanding Virtual Nodes on Cassandra 1.2

[aaron morton <aa...@thelastpickle.com>]

> Are there tickets/documents explain how data be replicated on Virtual Nodes?
This  http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2
Check the changes.txt file, they link to tickets. 

not many people use BOP so you may be exploring new'ish territory. Try asking someone on the IRC channel. 

Cheers
 
-----------------
Aaron Morton
Freelance Cassandra Developer
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 31/01/2013, at 11:47 PM, Manu Zhang <ow...@gmail.com> wrote:

> On Thu 31 Jan 2013 03:43:32 AM CST, Zhong Li wrote:
>> Are there tickets/documents explain how data be replicated on Virtual
>> Nodes? If there are multiple tokens on one physical host, may a chance
>> two or more tokens chosen by replication strategy located on same
>> host? If move/remove/add a token
>> manually, does Cassandra Engine validate the case?
>> 
>> Thanks.
>> 
>> 
>> On Jan 30, 2013, at 12:46 PM, Zhong Li wrote:
>> 
>>>> You add a physical node and that in turn adds num_token tokens to
>>>> the ring.
>>> 
>>> No, I am talking about Virtual Nodes with order preserving
>>> partitioner. For an existing host with multiple tokens setting list
>>> on cassandra.inital_token. After initial bootstrapping, the host will
>>> not aware changes of cassandra.inital_token. If I want add a new
>>> token( virtual node), I have to rebuild the host with new token list.
>>> 
>>> My question is if there is way to add a virtual nodes without rebuild it?
>>> 
>>> Thanks,
>>> 
>>> On Jan 30, 2013, at 10:21 AM, Manu Zhang wrote:
>>> 
>>>> On Wed 30 Jan 2013 02:29:27 AM CST, Zhong Li wrote:
>>>>> One more question, can I add a virtual node manually without reboot
>>>>> and rebuild a host data?
>>>>> 
>>>>> I checked nodetool command, there is no option to add a node.
>>>>> 
>>>>> Thanks.
>>>>> 
>>>>> Zhong
>>>>> 
>>>>> 
>>>>> On Jan 29, 2013, at 11:09 AM, Zhong Li wrote:
>>>>> 
>>>>>> I was misunderstood this
>>>>>> http://www.datastax.com/dev/blog/virtual-nodes-in-cassandra-1-2 ,
>>>>>> especially
>>>>>> "If you want to get started with vnodes on a fresh cluster, however,
>>>>>> that is fairly straightforward. Just don’t set the
>>>>>> |initial_token| parameter in your|conf/cassandra.yaml| and instead
>>>>>> enable the |num_tokens| parameter. A good default value for this
>>>>>> is 256"
>>>>>> 
>>>>>> Also I couldn't find document about set multiple tokens
>>>>>> for cassandra.inital_token
>>>>>> 
>>>>>> Anyway, I just tested, it does work to set  comma separated list of
>>>>>> tokens.
>>>>>> 
>>>>>> Thanks,
>>>>>> 
>>>>>> Zhong
>>>>>> 
>>>>>> 
>>>>>> On Jan 29, 2013, at 3:06 AM, aaron morton wrote:
>>>>>> 
>>>>>>>> After I searched some document on Datastax website and some old
>>>>>>>> ticket, seems that it works for random partitioner only, and leaves
>>>>>>>> order preserved partitioner out of the luck.
>>>>>>> Links ?
>>>>>>> 
>>>>>>>> or allow add Virtual Nodes manually?
>>>>>>> If not looked into it but there is a cassandra.inital_token startup
>>>>>>> param that takes a comma separated list of tokens for the node.
>>>>>>> 
>>>>>>> There also appears to be support for the ordered partitions to
>>>>>>> generate random tokens.
>>>>>>> 
>>>>>>> But you would still have the problem of having to balance your row
>>>>>>> keys around the token space.
>>>>>>> 
>>>>>>> Cheers
>>>>>>> -----------------
>>>>>>> Aaron Morton
>>>>>>> Freelance Cassandra Developer
>>>>>>> New Zealand
>>>>>>> 
>>>>>>> @aaronmorton
>>>>>>> http://www.thelastpickle.com <http://www.thelastpickle.com/>
>>>>>>> <http://www.thelastpickle.com/>
>>>>>>> 
>>>>>>> On 29/01/2013, at 10:31 AM, Zhong Li <zli@voxeo.com
>>>>>>> <ma...@voxeo.com>
>>>>>>> <ma...@voxeo.com>> wrote:
>>>>>>> 
>>>>>>>> Hi All,
>>>>>>>> 
>>>>>>>> Virtual Nodes is great feature. After I searched some document on
>>>>>>>> Datastax website and some old ticket, seems that it works for
>>>>>>>> random partitioner only, and leaves order preserved partitioner out
>>>>>>>> of the luck. I may misunderstand, please correct me. if it doesn't
>>>>>>>> love order preserved partitioner, would be possible to add support
>>>>>>>> multiple initial_token(s) for  order preserved partitioner  or
>>>>>>>> allow add Virtual Nodes manually?
>>>>>>>> 
>>>>>>>> Thanks,
>>>>>>>> 
>>>>>>>> Zhong
>>>>>>> 
>>>>>> 
>>>>> 
>>>> 
>>>> You add a physical node and that in turn adds num_token tokens to
>>>> the ring.
>>> 
>> 
> 
> no, those tokens will be skipped