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From Alain RODRIGUEZ <arodr...@gmail.com>
Subject Re: Adding datacenter for move to vnodes
Date Fri, 07 Feb 2014 12:57:23 GMT
@Bill

An other DC for this migration is the less impacting way to do it. You set
a new cluster, switch to it when it's ready. No performance or down time
issues.

Decommissioning a node is quite an heavy operation since it will give part
of its data to all the remaining nodes, increasing network, disk load and
data size on all the remaining nodes.

An other option is "cassandra-shuffle", but afaik, it never worked properly
and people recommend using a new cluster to switch.

@Andrey & Bill

I think you can mix vnodes with physical nodes, yet, you might have a node
with 99% of the data, since it will take care of a lot of ranges (256 ?)
while other nodes will take care of only 1. Might not be an issue on a dev
or demo cluster but it will certainly be in a production environnement.




2014-02-07 0:28 GMT+01:00 Andrey Ilinykh <ailinykh@gmail.com>:

> My understanding is you can't mix vnodes and regular nodes in the same DC.
> Is it correct?
>
>
>
> On Thu, Feb 6, 2014 at 2:16 PM, Vasileios Vlachos <
> vasileiosvlachos@gmail.com> wrote:
>
>> Hello,
>>
>> My question is why would you need another DC to migrate to Vnodes? How
>> about decommissioning each node in turn, changing the cassandra.yaml
>> accordingly, delete the data and bring the node back in the cluster and let
>> it bootstrap from the others?
>>
>> We did that recently with our demo cluster. Is that wrong in any way? The
>> only think to take into consideration is the disk space I think. We are not
>> using amazon, but I am not sure how would that be different for this
>> particular issue.
>>
>> Thanks,
>>
>> Bill
>> On 6 Feb 2014 16:34, "Alain RODRIGUEZ" <arodrime@gmail.com> wrote:
>>
>>> Glad it helps.
>>>
>>> Good luck with this.
>>>
>>> Cheers,
>>>
>>> Alain
>>>
>>>
>>> 2014-02-06 17:30 GMT+01:00 Katriel Traum <katriel@google.com>:
>>>
>>>> Thank you Alain! That was exactly what I was looking for. I was worried
>>>> I'd have to do a rolling restart to change the snitch.
>>>>
>>>> Katriel
>>>>
>>>>
>>>>
>>>> On Thu, Feb 6, 2014 at 1:10 PM, Alain RODRIGUEZ <arodrime@gmail.com>wrote:
>>>>
>>>>> Hi, we did this exact same operation here too, with no issue.
>>>>>
>>>>> Contrary to Paulo we did not modify our snitch.
>>>>>
>>>>> We simply added a "dc_suffix" in the property in
>>>>> cassandra-rackdc.properties conf file for nodes in the new cluster :
>>>>>
>>>>> # Add a suffix to a datacenter name. Used by the Ec2Snitch and
>>>>> Ec2MultiRegionSnitch
>>>>>
>>>>> # to append a string to the EC2 region name.
>>>>>
>>>>> dc_suffix=-xl
>>>>>
>>>>> So our new cluster DC is basically : eu-west-xl
>>>>>
>>>>> I think this is less risky, at least it is easier to do.
>>>>>
>>>>> Hope this help.
>>>>>
>>>>>
>>>>> 2014-02-02 11:42 GMT+01:00 Paulo Ricardo Motta Gomes <
>>>>> paulo.motta@chaordicsystems.com>:
>>>>>
>>>>> We had a similar situation and what we did was first migrate the 1.1
>>>>>> cluster to GossipingPropertyFileSnitch, making sure that for each
node we
>>>>>> specified the correct availability zone as the rack in
>>>>>> the cassandra-rackdc.properties. In this way,
>>>>>> the GossipingPropertyFileSnitch is equivalent to the EC2MultiRegionSnitch,
>>>>>> so the data location does not change and no repair is needed afterwards.
>>>>>> So, if your nodes are located in the us-east-1e AZ, your cassandra-rackdc.properties
>>>>>> should look like:
>>>>>>
>>>>>> dc=us-east
>>>>>> rack=1e
>>>>>>
>>>>>> After this step is complete on all nodes, then you can add a new
>>>>>> datacenter specifying different dc and rack on the
>>>>>> cassandra-rackdc.properties of the new DC. Make sure you upgrade
your
>>>>>> initial datacenter to 1.2 before adding a new datacenter with vnodes
>>>>>> enabled (of course).
>>>>>>
>>>>>> Cheers
>>>>>>
>>>>>>
>>>>>> On Sun, Feb 2, 2014 at 6:37 AM, Katriel Traum <katriel@google.com>wrote:
>>>>>>
>>>>>>> Hello list.
>>>>>>>
>>>>>>> I'm upgrading a 1.1 cassandra cluster to 1.2(.13).
>>>>>>> I've read here and in other places that the best way to migrate
to
>>>>>>> vnodes is to add a new DC, with the same amount of nodes, and
run rebuild
>>>>>>> on each of them.
>>>>>>> However, I'm faced with the fact that I'm using EC2MultiRegion
>>>>>>> snitch, which automagically creates the DC and RACK.
>>>>>>>
>>>>>>> Any ideas how I can go about adding a new DC with this kind of
>>>>>>> setup? I need these new machines to be in the same EC2 Region
as the
>>>>>>> current ones, so adding to a new Region is not an option.
>>>>>>>
>>>>>>> TIA,
>>>>>>> Katriel
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> *Paulo Motta*
>>>>>>
>>>>>> Chaordic | *Platform*
>>>>>> *www.chaordic.com.br <http://www.chaordic.com.br/>*
>>>>>> +55 48 3232.3200
>>>>>> +55 83 9690-1314
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>

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