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From Martin Xue <martin...@gmail.com>
Subject Re: What really happened during repair?
Date Sun, 04 Aug 2019 20:52:41 GMT
Hi Alex,

Thanks for pointing that out. yes I am running version 3.0.14. I ran
"nodetool repair -pr --full 1_TB_keyspace", and just tried to understand
more about what happened behind the things.

I am still puzzle with the questions above.

Any suggestions will be appreciated.

Thanks
Regards
Martin


On Sun, Aug 4, 2019 at 4:31 PM Alexander Dejanovski <alex@thelastpickle.com>
wrote:

> Hi Jeff,
>
> Anticompaction only runs before repair in the upcoming 4.0.
> In all other versions of Cassandra, it runs at the end of repair sessions.
> My understanding from other messages Martin sent to the ML was that he was
> already running full repair not incremental, which before 4.0 will also
> performs anticompaction (unless you use subrange).
>
> Cheers,
>
>
>
> Le dim. 4 août 2019 à 02:29, Jeff Jirsa <jjirsa@gmail.com> a écrit :
>
>>
>> > On Aug 3, 2019, at 5:03 PM, Martin Xue <martinxue@gmail.com> wrote:
>> >
>> > Hi Cassandra community,
>> >
>> > I am using Cassandra 3.0.14, 1 cluster, node a,b,c in DC1, node d,e,f
>> in DC2.
>> >
>> > Keyspace_m is 1TB
>> >
>> > When I run repair -pr a full keyspace_m on node a, what I noticed are:
>> > 1. Repair process is running on node a
>> > 2. Anti compaction after repair are running on other nodes at least
>> node b,d,e,f
>> >
>> > I want to know
>> > 1. why there are anti compactions running after repair?
>>
>>
>> They should run before repair - they split data you’re going to repair
>> from data you’re not going to repair
>>
>> If they’re running after, either there’s another repair command on
>> adjacent nodes or you’re repairing multiple key spaces and lost track
>>
>> > 2. Why it needs to run on other nodes? (I only run primary range repair
>> on node a)
>>
>> Every host involved in the repair will anticompact to split data in the
>> range you’re repairing from other data. That means RF number of hosts  will
>> run anticompaction for each range you repair
>> > 3. What's the purpose of anti compaction after repair?
>>
>> Answered above , but reminder it’s before
>>
>> > 4. Can I disable the anti compaction? If so any damage will cause? (It
>> takes more than 2 days to run on 1TB keyspace_m, and filled up disk
>> quickly, too time and resources consuming)
>>
>>
>> You can run full repair instead of incremental by passing -full
>>
>> But he cost of anticompaction should go down after the first successful
>> incremental repair
>>
>> >
>> > Any suggestions would be appreciated.
>> >
>> > Thanks
>> > Regards
>> > Martin
>>
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