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From Tyler Hobbs <ty...@datastax.com>
Subject Re: how to take consistant snapshot?
Date Fri, 07 Dec 2012 17:28:35 GMT
Snapshots trigger a flush first, so data that's currently in the commit log
will be covered by the snapshot.


On Thu, Dec 6, 2012 at 11:52 PM, Andrey Ilinykh <ailinykh@gmail.com> wrote:

>
>
>
> On Thu, Dec 6, 2012 at 7:34 PM, aaron morton <aaron@thelastpickle.com>wrote:
>
>> For background
>>
>>
>> http://wiki.apache.org/cassandra/Operations?highlight=%28snapshot%29#Consistent_backups<http://wiki.apache.org/cassandra/Operations?highlight=(snapshot)#Consistent_backups>
>>
>> If you it for a single node then yes there is a chance of inconsistency
>> across CF's.
>>
>> If you have mulitple nodes the snashots you take on the later nodes will
>> help. If you use CL QUOURM for reads you *may* be ok (cannot work it out
>> quickly.). If you use CL ALL for reads you will be ok. Or you can use
>> nodetool repair to ensure the data is consistent.
>>
>> I'm talking about restoring whole cluster, so all nodes are restored from
> backup and all of them are inconsistent because they lost data  from commit
> logs.  It doesn't matter what CL I use, some data may be lost.
> Cassandra 1.1 supports commit log archiving
> http://www.datastax.com/docs/1.1/configuration/commitlog_archiving
> I think if I store both flushed sstables and commit logs it should solve
> my problem. I'm wondering if someone has any experience with this feature?
>
> Thank you,
>   Andrey
>



-- 
Tyler Hobbs
DataStax <http://datastax.com/>

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