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From Neha Trivedi <nehajtriv...@gmail.com>
Subject Re: Cassandra Maintenance Best practices
Date Tue, 16 Dec 2014 17:10:19 GMT
Thanks Ryan.
So, as Jonathan recommended, we should have RF=3 with Three nodes.
So Quorum = 2 so, CL= 2 (or I need the CL to be set to two) and I will not
need the  downgrading retry policy, in case if my one node goes down.

I can dynamically add a New node to my Cluster.
Can I change my RF to 3, dynamically without affecting my nodes ?

regards
Neha

On Tue, Dec 16, 2014 at 10:32 PM, Ryan Svihla <rsvihla@datastax.com> wrote:
>
>
> CL quorum with RF2 is equivalent to ALL, writes will require
> acknowledgement from both nodes, and reads will be from both nodes.
>
> CL one will write to both replicas, but return success as soon as the
> first one responds, read will be from one node ( load balancing strategy
> determines which one).
>
> FWIW I've come around to dislike downgrading retry policy. I now feel like
> if I'm using downgrading, I'm effectively going to be using that downgraded
> policy most of the time under server stress, so in practice that reduced
> consistency is the effective consistency I'm asking for from my writes and
> reads.
>
>
>
> On Tue, Dec 16, 2014 at 10:50 AM, Neha Trivedi <nehajtrivedi@gmail.com>
> wrote:
>>
>> Hi Jonathan,QUORUM = (sum_of_replication_factors / 2) + 1, For us Quorum
>> = (2/2) +1 = 2.
>>
>> Default CL is ONE and RF=2 with Two Nodes in the cluster.(I am little
>> confused, what is my read CL and what is my WRITE CL?)
>>
>> So, does it mean that for every WRITE it will write in both the nodes?
>>
>> and For every READ, it will read from both nodes and give back to client?
>>
>> DOWNGRADERETRYPOLICY will downgrade the CL if a node is down?
>>
>> Regards
>>
>> Neha
>>
>> On Wed, Dec 10, 2014 at 1:00 PM, Jonathan Haddad <jon@jonhaddad.com>
>> wrote:
>>>
>>> I did a presentation on diagnosing performance problems in production at
>>> the US & Euro summits, in which I covered quite a few tools & preventative
>>> measures you should know when running a production cluster.  You may find
>>> it useful:
>>> http://rustyrazorblade.com/2014/09/cassandra-summit-recap-diagnosing-problems-in-production/
>>>
>>> On ops center - I recommend it.  It gives you a nice dashboard.  I don't
>>> think it's completely comprehensive (but no tool really is) but it gets you
>>> 90% of the way there.
>>>
>>> It's a good idea to run repairs, especially if you're doing deletes or
>>> querying at CL=ONE.  I assume you're not using quorum, because on RF=2
>>> that's the same as CL=ALL.
>>>
>>> I recommend at least RF=3 because if you lose 1 server, you're on the
>>> edge of data loss.
>>>
>>>
>>> On Tue Dec 09 2014 at 7:19:32 PM Neha Trivedi <nehajtrivedi@gmail.com>
>>> wrote:
>>>
>>>> Hi,
>>>> We have Two Node Cluster Configuration in production with RF=2.
>>>>
>>>> Which means that the data is written in both the clusters and it's
>>>> running for about a month now and has good amount of data.
>>>>
>>>> Questions?
>>>> 1. What are the best practices for maintenance?
>>>> 2. Is OPScenter required to be installed or I can manage with nodetool
>>>> utility?
>>>> 3. Is is necessary to run repair weekly?
>>>>
>>>> thanks
>>>> regards
>>>> Neha
>>>>
>>>
>
> --
>
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>
> Ryan Svihla
>
> Solution Architect
>
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>
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