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Posted to user@cassandra.apache.org by laxmikanth sadula <la...@gmail.com> on 2016/08/27 16:45:45 UTC
New data center to an existing cassandra cluster
Hi,
I'm going to add a new data center DC3 to an existing cassandra cluster
which has already 2 data centers DC1 , DC2.
The thing I'm worried of is about tables in one keyspace which has QUORUM
reads and NOT LOCAL_QUORUM.
So while adding a new data centers with auto_bootstrap:false and 'nodetool
rebuild' , will the queries to tables in this keyspace will have any issue ?
Thanks in advance.
--
Regards,
Laxmikanth
Re: New data center to an existing cassandra cluster
Posted by Jeff Jirsa <je...@crowdstrike.com>.
If you’ve repaired at the point you alter keyspace to add the third DC, and you write with quorum, and your RF per DC is the same (for example, 3 in each DC), then you’ll likely get valid read requests, as long as none of the other nodes go down while you rebuild.
There are a lot of IFs and ANDs in that statement. Be sure you hit ALL of them or you may miss data on reads.
From: laxmikanth sadula <la...@gmail.com>
Reply-To: "user@cassandra.apache.org" <us...@cassandra.apache.org>
Date: Saturday, August 27, 2016 at 9:45 AM
To: "user@cassandra.apache.org" <us...@cassandra.apache.org>
Subject: New data center to an existing cassandra cluster
Hi,
I'm going to add a new data center DC3 to an existing cassandra cluster which has already 2 data centers DC1 , DC2.
The thing I'm worried of is about tables in one keyspace which has QUORUM reads and NOT LOCAL_QUORUM.
So while adding a new data centers with auto_bootstrap:false and 'nodetool rebuild' , will the queries to tables in this keyspace will have any issue ?
Thanks in advance.
--
Regards,
Laxmikanth
Re: New data center to an existing cassandra cluster
Posted by laxmikanth sadula <la...@gmail.com>.
Yes , RF=3 in existing datacenters DC1 & DC2 and going to be same RF in
new datacenter DC3 which I'm going to add.
On Sat, Aug 27, 2016 at 11:15 PM, Alexander DEJANOVSKI <
adejanovski@gmail.com> wrote:
> Reads at quorum in dc3 will involve dc1 and dc2 as they will require a
> response from more than half the replicas throughout the Cluster.
>
> If you're using RF=3 in each DC, each read will need at least 5 responses,
> which DC3 cannot provide on its own.
>
> You can have troubles if DC3 has more than half then replicas, but I
> guess/hope it is not the case, otherwise you're fine.
>
> You would be in trouble though if you were using local_quorum on DC3 or
> ONE on any DC.
>
>
>
> Le sam. 27 août 2016 19:11, Surbhi Gupta <su...@gmail.com> a
> écrit :
>
>> Yes, it will have issue during the time new nodes are building....
>> So it is always advised to use LOCAL_QUORUM instead of QUORUM and
>> LOCAL_ONE instead of ONE
>>
>> On 27 August 2016 at 09:45, laxmikanth sadula <la...@gmail.com>
>> wrote:
>>
>>> Hi,
>>>
>>> I'm going to add a new data center DC3 to an existing cassandra cluster
>>> which has already 2 data centers DC1 , DC2.
>>>
>>> The thing I'm worried of is about tables in one keyspace which has
>>> QUORUM reads and NOT LOCAL_QUORUM.
>>> So while adding a new data centers with auto_bootstrap:false and
>>> 'nodetool rebuild' , will the queries to tables in this keyspace will have
>>> any issue ?
>>>
>>> Thanks in advance.
>>>
>>> --
>>> Regards,
>>> Laxmikanth
>>>
>>
>>
--
Regards,
Laxmikanth
99621 38051
Re: New data center to an existing cassandra cluster
Posted by Alexander DEJANOVSKI <ad...@gmail.com>.
Reads at quorum in dc3 will involve dc1 and dc2 as they will require a
response from more than half the replicas throughout the Cluster.
If you're using RF=3 in each DC, each read will need at least 5 responses,
which DC3 cannot provide on its own.
You can have troubles if DC3 has more than half then replicas, but I
guess/hope it is not the case, otherwise you're fine.
You would be in trouble though if you were using local_quorum on DC3 or ONE
on any DC.
Le sam. 27 août 2016 19:11, Surbhi Gupta <su...@gmail.com> a
écrit :
> Yes, it will have issue during the time new nodes are building....
> So it is always advised to use LOCAL_QUORUM instead of QUORUM and
> LOCAL_ONE instead of ONE
>
> On 27 August 2016 at 09:45, laxmikanth sadula <la...@gmail.com>
> wrote:
>
>> Hi,
>>
>> I'm going to add a new data center DC3 to an existing cassandra cluster
>> which has already 2 data centers DC1 , DC2.
>>
>> The thing I'm worried of is about tables in one keyspace which has QUORUM
>> reads and NOT LOCAL_QUORUM.
>> So while adding a new data centers with auto_bootstrap:false and
>> 'nodetool rebuild' , will the queries to tables in this keyspace will have
>> any issue ?
>>
>> Thanks in advance.
>>
>> --
>> Regards,
>> Laxmikanth
>>
>
>
Re: New data center to an existing cassandra cluster
Posted by Surbhi Gupta <su...@gmail.com>.
Yes, it will have issue during the time new nodes are building....
So it is always advised to use LOCAL_QUORUM instead of QUORUM and LOCAL_ONE
instead of ONE
On 27 August 2016 at 09:45, laxmikanth sadula <la...@gmail.com>
wrote:
> Hi,
>
> I'm going to add a new data center DC3 to an existing cassandra cluster
> which has already 2 data centers DC1 , DC2.
>
> The thing I'm worried of is about tables in one keyspace which has QUORUM
> reads and NOT LOCAL_QUORUM.
> So while adding a new data centers with auto_bootstrap:false and 'nodetool
> rebuild' , will the queries to tables in this keyspace will have any issue ?
>
> Thanks in advance.
>
> --
> Regards,
> Laxmikanth
>