We did the test with ES still running and indexing data, ES still 
running/not indexing, and ES stopped. All three showed the poor i/o rate. 
Then after a few minutes, the copy i/o rate somehow increased again. It was 
really strange. We still have some digging to do to figure out the problem 
there.

On Sunday, July 13, 2014 2:33:00 AM UTC-7, Michael McCandless wrote:
>
> On Fri, Jul 11, 2014 at 7:35 PM, Kireet Reddy <[email protected] 
> <javascript:>> wrote:
>
>> The problem reappeared. We did some tests today around copying a large 
>> file on the nodes to test i/o throughput. On the loaded node, the copy was 
>> really slow, maybe 30x slower. So it seems your suspicion around something 
>> external interfering with I/O was right in the end even though nothing else 
>> is running on the machines. We will investigate our setup further but this 
>> doesn't seem like a lucene/elasticsearch issue in the end.
>>
>
> Hmm but ES was still running on the node?  So it could still be something 
> about ES/Lucene that's putting heaving IO load on the box?
>  
>
>> For the index close, I didn't issue any command, elasticsearch seemed to 
>> do that on its own. The code is in IndexingMemoryController. The triggering 
>> event seems to be the ram buffer size change, this triggers a call to 
>> InternalEngine.updateIndexingBufferSize() which then calls flush with type 
>> NEW_WRITER. That seems to close the lucene IndexWriter.
>>
>
> Ahh, thanks for the clarification, yes ES sometimes closes & opens a new 
> writer to make "non-live" settings changes take effect. However, changing 
> RAM buffer size for indexing is a live setting so it should not require the 
> close/open yet indeed (InternalEngine.updateIndexingBufferSize) it does ... 
> I'll dig.
>
> Mike McCandless
>
> http://blog.mikemccandless.com
>
>

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