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From Saad Mufti <saad.mu...@gmail.com>
Subject Re: Slow sync cost
Date Tue, 26 Apr 2016 00:52:56 GMT
Thanks, the meaning makes sense now but I still need to figure out why we
keep seeing this. How would I know if this is just us overloading the
capacity of our system with too much write load vs some configuration
problem?

Thanks.

----
Saad

On Mon, Apr 25, 2016 at 4:25 PM, Ted Yu <yuzhihong@gmail.com> wrote:

> 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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