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Posted to user@cassandra.apache.org by aaron morton <aa...@thelastpickle.com> on 2011/04/01 13:45:26 UTC
Re: changing replication strategy and effects on replica nodes
See the section on Replication here http://wiki.apache.org/cassandra/Operations#Replication It talks about how to change the RF and then says you can do the same when change the placement strategy.
It can be done, but is a little messy.
Depending on your setup it may also be possible to copy / move the nodes manually by moving sstable files.
I've not done it myself, are you able to run a test ?
Hope that helps.
Aaron
On 1 Apr 2011, at 02:04, Jonathan Colby wrote:
>
> From my understanding of replica copies, cassandra picks which nodes to replicate the data based on replication strategy, and those same "replica partner" nodes are always used according to token ring distribution.
>
> If you change the replication strategy, does cassandra pick new nodes to replicate to? (for example if you went from simple strategy to a networkTopology strategy where copies are to be sent to another datacenter)
>
> If so, do you now have unused replica data on the "old" replica nodes that you need to clean up manually?
Re: changing replication strategy and effects on replica nodes
Posted by aaron morton <aa...@thelastpickle.com>.
You may do, if a node is no longer a replica for a token range. Which would be similar to reducing the RF.
nodetool cleanup is the thing to run after you have repaired to remove data a node should no longer have.
Aaron
On 1 Apr 2011, at 23:10, Jonathan Colby wrote:
> Hi Aaron - Yes, I've read the part about changing the replication factor on a running cluster. I've even done it without a problem. My real point of my question was ....
>
>> do you now have unused replica data on the "old" replica nodes that you need to clean up manually?
>
> any insight would be appreciated.
>
> On Apr 1, 2011, at 1:45 PM, aaron morton wrote:
>
>> See the section on Replication here http://wiki.apache.org/cassandra/Operations#Replication It talks about how to change the RF and then says you can do the same when change the placement strategy.
>>
>> It can be done, but is a little messy.
>>
>> Depending on your setup it may also be possible to copy / move the nodes manually by moving sstable files.
>>
>> I've not done it myself, are you able to run a test ?
>>
>> Hope that helps.
>> Aaron
>>
>> On 1 Apr 2011, at 02:04, Jonathan Colby wrote:
>>
>>>
>>> From my understanding of replica copies, cassandra picks which nodes to replicate the data based on replication strategy, and those same "replica partner" nodes are always used according to token ring distribution.
>>>
>>> If you change the replication strategy, does cassandra pick new nodes to replicate to? (for example if you went from simple strategy to a networkTopology strategy where copies are to be sent to another datacenter)
>>>
>>> If so, do you now have unused replica data on the "old" replica nodes that you need to clean up manually?
>>
>
Re: changing replication strategy and effects on replica nodes
Posted by Jonathan Colby <jo...@gmail.com>.
Hi Aaron - Yes, I've read the part about changing the replication factor on a running cluster. I've even done it without a problem. My real point of my question was ....
> do you now have unused replica data on the "old" replica nodes that you need to clean up manually?
any insight would be appreciated.
On Apr 1, 2011, at 1:45 PM, aaron morton wrote:
> See the section on Replication here http://wiki.apache.org/cassandra/Operations#Replication It talks about how to change the RF and then says you can do the same when change the placement strategy.
>
> It can be done, but is a little messy.
>
> Depending on your setup it may also be possible to copy / move the nodes manually by moving sstable files.
>
> I've not done it myself, are you able to run a test ?
>
> Hope that helps.
> Aaron
>
> On 1 Apr 2011, at 02:04, Jonathan Colby wrote:
>
>>
>> From my understanding of replica copies, cassandra picks which nodes to replicate the data based on replication strategy, and those same "replica partner" nodes are always used according to token ring distribution.
>>
>> If you change the replication strategy, does cassandra pick new nodes to replicate to? (for example if you went from simple strategy to a networkTopology strategy where copies are to be sent to another datacenter)
>>
>> If so, do you now have unused replica data on the "old" replica nodes that you need to clean up manually?
>