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From Ted Yu <yuzhih...@gmail.com>
Subject Re: Slow sync cost
Date Mon, 25 Apr 2016 20:25:21 GMT
w.r.t. the pipeline, please see this description:

http://itm-vm.shidler.hawaii.edu/HDFS/ArchDocUseCases.html

On Mon, Apr 25, 2016 at 12:18 PM, Saad Mufti <saad.mufti@gmail.com> wrote:

> Hi,
>
> In our large HBase cluster based on CDH 5.5 in AWS, we're constantly seeing
> the following messages in the region server logs:
>
> 2016-04-25 14:02:55,178 INFO
> org.apache.hadoop.hbase.regionserver.wal.FSHLog: Slow sync cost: 258 ms,
> current pipeline:
> [DatanodeInfoWithStorage[10.99.182.165:50010
> ,DS-281d4c4f-23bd-4541-bedb-946e57a0f0fd,DISK],
> DatanodeInfoWithStorage[10.99.182.236:50010
> ,DS-f8e7e8c9-6fa0-446d-a6e5-122ab35b6f7c,DISK],
> DatanodeInfoWithStorage[10.99.182.195:50010
> ,DS-3beae344-5a4a-4759-ad79-a61beabcc09d,DISK]]
>
>
> These happen regularly while HBase appear to be operating normally with
> decent read and write performance. We do have occasional performance
> problems when regions are auto-splitting, and at first I thought this was
> related but now I se it happens all the time.
>
>
> Can someone explain what this means really and should we be concerned? I
> tracked down the source code that outputs it in
>
>
> hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java
>
> but after going through the code I think I'd need to know much more about
> the code to glean anything from it or the associated JIRA ticket
> https://issues.apache.org/jira/browse/HBASE-11240.
>
> Also, what is this "pipeline" the ticket and code talks about?
>
> Thanks in advance for any information and/or clarification anyone can
> provide.
>
> ----
>
> Saad
>

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