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From Tyler Hobbs <ty...@datastax.com>
Subject Re: how to take consistant snapshot?
Date Fri, 07 Dec 2012 20:38:22 GMT
Right.  I don't personally think incremental backup is useful beyond
restoring individual nodes unless none of your data happens to reference
any other rows.


On Fri, Dec 7, 2012 at 11:37 AM, Andrey Ilinykh <ailinykh@gmail.com> wrote:

> That's right. But when I have incremental backup on each CF gets flushed
> independently. I have "hot" CF which gets flushed every several minutes and
> regular CF which gets flushed every hour or so. They have references to
> each other and data in sstables is definitely inconsistent.
>
>
>
> On Fri, Dec 7, 2012 at 9:28 AM, Tyler Hobbs <tyler@datastax.com> wrote:
>
>> 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/>
>>
>>
>


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

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