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Posted to user@cassandra.apache.org by Senthilvel Rangaswamy <se...@gmail.com> on 2012/08/22 17:37:49 UTC
nodetool repair - when is it not needed ?
We are running Cassandra 1.1.2 on EC2. Our database is primarily all
counters and we don't do any
deletes.
Does nodetool repair do anything for such a database. All the docs I read
for nodetool repair suggests
that nodetool repair is needed only if there is deletes.
Thanks,
Senthil
Re: nodetool repair - when is it not needed ?
Posted by aaron morton <aa...@thelastpickle.com>.
> Also when hints are replayed they are sent of as mutations, which may still be dropped by the target if they are not serviced before rpc_timeout. Sending nodes throttle their requests so it's unlikely but possible.
My bad there. I thought the mutations were send one way.
When node is sending hints it waits the normal rpc_timeout. If there is a time out hint delivery for that endpoint is aborted. It will be re-tried the in the next HH round, which is every 10 minutes.
Cheers
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com
On 23/08/2012, at 9:36 PM, aaron morton <aa...@thelastpickle.com> wrote:
> HH works to a point. Specifically, it only collects hints for the first hour the node is down and it has a safety valve to avoid the node collecting hints getting overwhelmed. Looking at the code it takes a bit for that the trip and you would get a TimeoutException coming back.
>
> Also when hints are replayed they are sent of as mutations, which may still be dropped by the target if they are not serviced before rpc_timeout. Sending nodes throttle their requests so it's unlikely but possible.
>
> HH is is much more robust, but AFAIK repair is still _the_ way to ensure on disk consistency.
>
> Cheers
>
> -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 23/08/2012, at 6:59 AM, Rob Coli <rc...@palominodb.com> wrote:
>
>> On Wed, Aug 22, 2012 at 8:37 AM, Senthilvel Rangaswamy
>> <se...@gmail.com> wrote:
>>> We are running Cassandra 1.1.2 on EC2. Our database is primarily all
>>> counters and we don't do any
>>> deletes.
>>>
>>> Does nodetool repair do anything for such a database. All the docs I read
>>> for nodetool repair suggests
>>> that nodetool repair is needed only if there is deletes.
>>
>> Since 1.0, repair is only needed if a node crashes. If a node crashes,
>> my understanding is that a cluster-wide repair (with -pr on each node)
>> is required, because the crashed node could have lost a hint for any
>> other node.
>>
>> https://issues.apache.org/jira/browse/CASSANDRA-2034
>>
>> =Rob
>>
>> --
>> =Robert Coli
>> AIM>ALK - rcoli@palominodb.com
>> YAHOO - rcoli.palominob
>> SKYPE - rcoli_palominodb
>
Re: nodetool repair - when is it not needed ?
Posted by aaron morton <aa...@thelastpickle.com>.
HH works to a point. Specifically, it only collects hints for the first hour the node is down and it has a safety valve to avoid the node collecting hints getting overwhelmed. Looking at the code it takes a bit for that the trip and you would get a TimeoutException coming back.
Also when hints are replayed they are sent of as mutations, which may still be dropped by the target if they are not serviced before rpc_timeout. Sending nodes throttle their requests so it's unlikely but possible.
HH is is much more robust, but AFAIK repair is still _the_ way to ensure on disk consistency.
Cheers
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com
On 23/08/2012, at 6:59 AM, Rob Coli <rc...@palominodb.com> wrote:
> On Wed, Aug 22, 2012 at 8:37 AM, Senthilvel Rangaswamy
> <se...@gmail.com> wrote:
>> We are running Cassandra 1.1.2 on EC2. Our database is primarily all
>> counters and we don't do any
>> deletes.
>>
>> Does nodetool repair do anything for such a database. All the docs I read
>> for nodetool repair suggests
>> that nodetool repair is needed only if there is deletes.
>
> Since 1.0, repair is only needed if a node crashes. If a node crashes,
> my understanding is that a cluster-wide repair (with -pr on each node)
> is required, because the crashed node could have lost a hint for any
> other node.
>
> https://issues.apache.org/jira/browse/CASSANDRA-2034
>
> =Rob
>
> --
> =Robert Coli
> AIM>ALK - rcoli@palominodb.com
> YAHOO - rcoli.palominob
> SKYPE - rcoli_palominodb
Re: nodetool repair - when is it not needed ?
Posted by Rob Coli <rc...@palominodb.com>.
On Wed, Aug 22, 2012 at 8:37 AM, Senthilvel Rangaswamy
<se...@gmail.com> wrote:
> We are running Cassandra 1.1.2 on EC2. Our database is primarily all
> counters and we don't do any
> deletes.
>
> Does nodetool repair do anything for such a database. All the docs I read
> for nodetool repair suggests
> that nodetool repair is needed only if there is deletes.
Since 1.0, repair is only needed if a node crashes. If a node crashes,
my understanding is that a cluster-wide repair (with -pr on each node)
is required, because the crashed node could have lost a hint for any
other node.
https://issues.apache.org/jira/browse/CASSANDRA-2034
=Rob
--
=Robert Coli
AIM>ALK - rcoli@palominodb.com
YAHOO - rcoli.palominob
SKYPE - rcoli_palominodb