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From Jared Laprise <ja...@webonyx.com>
Subject RE: URGENT HELP PLEASE!
Date Fri, 25 Mar 2011 05:07:33 GMT
Correct, replication factor of 1. 

I've been reading and researching as fast as possible so I'm also starting to realize what
some of the configurations actually mean and getting a clearer picture. My request to the
Cassandra community was a desperate, "Oh man! I F'd up!" moment, and didn't have the time
to Google it myself :-)


-----Original Message-----
From: Jonathan Ellis [mailto:jbellis@gmail.com] 
Sent: Thursday, March 24, 2011 9:49 PM
To: user@cassandra.apache.org
Cc: Jared Laprise; aaron morton
Subject: Re: URGENT HELP PLEASE!

Each row is replicated to replication_factor nodes, not the entire cluster (or you couldn't
scale writes by adding machines).

Sounds like you're running with RF=1.

On Thu, Mar 24, 2011 at 10:44 PM, Jared Laprise <jared@webonyx.com> wrote:
> Thanks for the responses. I got everything working again, and have some ideas on why
but am not completely sure.
>
> How I got it working again was simply bring the second node back online. I was under
the assumption that all data is replicated between nodes (eventually). Am I incorrect? It
would seem that each node stores different data and delegates the read request to whichever
node holds the data. Although I've spent a lot of time with Cassandra in a single node environment
I think I may be lacking a bit of understanding on how Cassandra behaves in a clustered environment.
>
>
> -----Original Message-----
> From: Jonathan Ellis [mailto:jbellis@gmail.com]
> Sent: Thursday, March 24, 2011 8:22 PM
> To: user@cassandra.apache.org
> Cc: aaron morton
> Subject: Re: URGENT HELP PLEASE!
>
> Right, Cassandra doesn't keep old versions around so to see an old version you have to
have uncompacted data and whack the new data -- either by blowing away sstables or not replaying
the commitlog.
>
> Snapshots flush before creating their hard links, which rules out any commitlog problems.
>
> If you ran out of disk space you wouldn't get past the commitlog append, so you'd never
get new data in at all after that.
>
> Sounds like an environmental problem, not Cassandra specific.
>
> On Thu, Mar 24, 2011 at 9:10 PM, aaron morton <aaron@thelastpickle.com> wrote:
>> Was there anything in the server logs during startup ?
>> I've not heard of this happening before and it's hard think of how / 
>> why cassandra could revert it's data. Other than something external 
>> playing with the files on disk Aaron On 25 Mar 2011, at 13:49, Jared 
>> Laprise wrote:
>>
>> Hello all, I'm running 2 Cassandra 6.5 nodes and I brought down the 
>> secondary node and restarted the primary node. After Cassandra came 
>> back up all data has been reverted to several months ago.
>>
>> I could really use some incite here, this is a production website and 
>> I need to act quickly. I have a cron job that takes a snapshot every 
>> night, but even with that I tried to restore a snapshot on my local 
>> development environment and it was also missing a ton of data.
>>
>> Any help will be so appreciated.
>>
>>
>>
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of DataStax, the source for professional Cassandra support 
> http://www.datastax.com
>



--
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support http://www.datastax.com

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