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From Ali Hubail <Ali.Hub...@petrolink.com>
Subject Re: Compaction Strategy
Date Thu, 20 Sep 2018 17:53:00 GMT
Hello Rajasekhar,

It's not really clear to me what your workload is. As I understand it, you 
do heavy writes, but what about reads?
So, could you:

1) execute 
nodetool tablestats 
nodetool tablehistograms
nodetool compactionstats

we should be able to see the latency, workload type, and the # of sstable 
used for reads

2) specify your hardware specs. i.e., memory size, cpu, # of drives (for 
data sstables), and type of harddrives (ssd/hdd)
3) cassandra.yaml (make sure to sanitize it)

You have a lot of updates, and your data is most likely scattered across 
different sstables. size compaction strategy (STCS) is much less expensive 
than level compaction strategy (LCS). 

Stopping the background compaction should be approached with caution, I 
think your problem is more to do with why STCS compaction is taking more 
resources than you expect.

Regards,

Ali Hubail

Petrolink International Ltd
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rajasekhar kommineni <rajacoast@gmail.com> 
09/19/2018 04:44 PM
Please respond to
user@cassandra.apache.org


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Subject
Re: Compaction Strategy






Hello,

Can any one respond to my questions. Is it a good idea to disable auto 
compaction and schedule it every 3 days. I am unable to control compaction 
and it is causing timeouts. 

Also will reducing or increasing compaction_throughput_mb_per_sec 
eliminate timeouts ?

Thanks,


> On Sep 17, 2018, at 9:38 PM, rajasekhar kommineni <rajacoast@gmail.com> 
wrote:
> 
> Hello Folks,
> 
> I need advice in deciding the compaction strategy for my C cluster. 
There are multiple jobs that will load the data with less inserts and more 
updates but no deletes. Currently I am using Size Tired compaction, but 
seeing auto compactions after the data load kicks, and also read timeouts 
during compaction.
> 
> Can anyone suggest good compaction strategy for my cluster which will 
reduce the timeouts.
> 
> 
> Thanks,
> 


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