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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: Really have to repair ?
Date Mon, 08 Apr 2013 14:48:30 GMT
Because cassandra is eventually consistent, and there are many settings
QUORUM, ONE, hint windows, disk failures, cosmic rays, node joins, there
are few absolutes.


On Mon, Apr 8, 2013 at 10:15 AM, <cscetbon.ext@orange.com> wrote:

> So, you're saying that deleted rows can come back even if the node is
> always up or down for less than max_hint_window_in_ms, right ?
>
> --
> Cyril SCETBON
>
> On Apr 5, 2013, at 11:59 PM, Edward Capriolo <edlinuxguru@gmail.com>
> wrote:
>
> There are a series of edge cases that dictate the need for repair. The
> largest cases are 1) lost deletes 2) random disk corruptions
>
> In our use case we only delete entire row keys, and if the row key comes
> back it is not actually a problem because our software will find it an
> delete it again. In those places we dodge running repair believe it or not.
>
> Edward
>
>
> On Fri, Apr 5, 2013 at 11:22 AM, Jean-Armel Luce <jaluce06@gmail.com>wrote:
>
>> Hi Cyril,
>>
>> According to the documentation (
>> http://wiki.apache.org/cassandra/Operations#Frequency_of_nodetool_repair),
>> I understand that is is not necessary to repair every node before
>> gc_grace_seconds if you are sure that you don't miss to run a repair each
>> time a node is down longer than gc_grace_seconds.
>>
>> "*IF* your operations team is sufficiently on the ball, you can get by
>> without repair as long as you do not have hardware failure -- in that case,
>> HintedHandoff is adequate to repair successful updates that some replicas
>> have missed"
>>
>> Am I wrong ? Thoughts ?
>>
>>
>>
>>
>> 2013/4/4 <cscetbon.ext@orange.com>
>>
>>> Hi,
>>>
>>> I know that deleted rows can reappear if "node repair" is not run on
>>> every node before *gc_grace_seconds* seconds. However do we really need
>>> to obey this rule if we run "node repair" on node that are down for more
>>> than *max_hint_window_in_ms* milliseconds ?
>>>
>>> Thanks
>>>  --
>>> Cyril SCETBON
>>>
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>
> _________________________________________________________________________________________________________________________
>
> Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou
privilegiees et ne doivent donc
> pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message
par erreur, veuillez le signaler
> a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques
etant susceptibles d'alteration,
> France Telecom - Orange decline toute responsabilite si ce message a ete altere, deforme
ou falsifie. Merci.
>
> This message and its attachments may contain confidential or privileged information that
may be protected by law;
> they should not be distributed, used or copied without authorisation.
> If you have received this email in error, please notify the sender and delete this message
and its attachments.
> As emails may be altered, France Telecom - Orange is not liable for messages that have
been modified, changed or falsified.
> Thank you.
>
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