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From Yan Chunlu <springri...@gmail.com>
Subject Re: node repair eat up all disk io and slow down entire cluster(3 nodes)
Date Thu, 21 Jul 2011 11:17:58 GMT
after tried nodetool -h reagon repair key cf, I found that even repair
single CF, it involves rebuild all sstables(using nodetool compactionstats),
is that normal?

On Thu, Jul 21, 2011 at 7:56 AM, Aaron Morton <aaron@thelastpickle.com>wrote:

> If you have never run repair also check the section on repair on this page
> http://wiki.apache.org/cassandra/Operations About how frequently it should
> be run.
>
> There is an issue where repair can stream too much data, and this can lead
> to excessive disk use.
>
> My non scientific approach to the never run repair before problem is to
> repair a single CF at a time, starting with the small ones that are less
> likely to have differences as they will stream the smallest amount of data.
>
> If you really want to conserve disk IO during the repair consider disabling
> the minor compaction by setting the min and max thresholds to 0 via node
> tool.
>
> hope that helps.
>
>
> -----------------
> Aaron Morton
> Freelance Cassandra Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 20/07/2011, at 11:46 PM, Yan Chunlu <springrider@gmail.com> wrote:
>
> just found this:
> <https://issues.apache.org/jira/browse/CASSANDRA-2156>
> https://issues.apache.org/jira/browse/CASSANDRA-2156
>
> but seems only available to 0.8 and people submitted a patch for 0.6, I am
> using 0.7.4, do I need to dig into the code and make my own patch?
>
> does add compaction throttle solve the io problem?  thanks!
>
> On Wed, Jul 20, 2011 at 4:44 PM, Yan Chunlu < <springrider@gmail.com>
> springrider@gmail.com> wrote:
>
>> at the beginning of using cassandra, I have no idea that I should run
>> "node repair" frequently, so basically, I have 3 nodes with RF=3 and have
>> not run node repair for months, the data size is 20G.
>>
>> the problem is when I start running node repair now, it eat up all disk io
>> and the server load became 20+ and increasing, the worst thing is, the
>> entire cluster has slowed down and can not handle request. so I have to stop
>> it immediately because it make my web service unavailable.
>>
>> the server has Intel Xeon-Lynnfield 3470-Quadcore [2.93GHz] and 8G
>> memory, with Western Digital WD RE3 WD1002FBYS SATA disk.
>>
>> I really have no idea what to do now, as currently I have already found
>> some data loss, any suggestions would be appreciated.
>>
>
>
>
> --
> 闫春路
>
>


-- 
闫春路

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