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From Jeff Jirsa <jji...@gmail.com>
Subject Re: Self-healing data integrity?
Date Sat, 09 Sep 2017 20:06:47 GMT
(Which isn't to say that someone shouldn't implement this; they should, and there's probably
a JIRA to do so already written, but it's a project of volunteers, and nobody has volunteered
to do the work yet)

-- 
Jeff Jirsa


> On Sep 9, 2017, at 12:59 PM, Jeff Jirsa <jjirsa@gmail.com> wrote:
> 
> There is, but they aren't consulted on the streaming paths (only on normal reads)
> 
> 
> -- 
> Jeff Jirsa
> 
> 
>> On Sep 9, 2017, at 12:02 PM, DuyHai Doan <doanduyhai@gmail.com> wrote:
>> 
>> Jeff,
>> 
>>  With default compression enabled on each table, isn't there CRC files created along
side with SSTables that can help detecting bit-rot ?
>> 
>> 
>>> On Sat, Sep 9, 2017 at 7:50 PM, Jeff Jirsa <jjirsa@gmail.com> wrote:
>>> Cassandra doesn't do that automatically - it can guarantee consistency on read
or write via ConsistencyLevel on each query, and it can run active (AntiEntropy) repairs.
But active repairs must be scheduled (by human or cron or by third party script like http://cassandra-reaper.io/),
and to be pedantic, repair only fixes consistency issue, there's some work to be done to properly
address/support fixing corrupted replicas (for example, repair COULD send a bit flip from
one node to all of the others)
>>> 
>>> 
>>> 
>>> -- 
>>> Jeff Jirsa
>>> 
>>> 
>>>> On Sep 9, 2017, at 1:07 AM, Ralph Soika <ralph.soika@imixs.com> wrote:
>>>> 
>>>> Hi,
>>>> 
>>>> I am searching for a big data storage solution for the Imixs-Workflow project.
I started with Hadoop until I became aware       of the 'small-file-problem'. So I am considering
using Cassandra now. 
>>>> But Hadoop has one important feature for me. The replicator continuously
examines whether data blocks are consistent across all datanodes. This will detect disk errors
and automatically move data from defective blocks to working blocks. I think this is called
'self-healing mechanism'.
>>>> Is there a similar feature in Cassandra too?
>>>> 
>>>> Thanks for help
>>>> 
>>>> Ralph
>>>> 
>>>> 
>>>> 
>>>> -- 
>>>> 
>> 

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