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From Xiaobing Zhou <xzho...@gmail.com>
Subject Re: HDFS Balancer - Balancing Effectively ?
Date Thu, 11 Aug 2016 17:56:20 GMT
They are working if you removed the last digit of the links.

On Thu, Aug 11, 2016 at 10:49 AM, Zhe Zhang <zhz@apache.org> wrote:

> Thanks Nicholas for the pointers; the first 2 links are not working.
>
> On Thu, Aug 11, 2016 at 10:09 AM Tsz Wo Sze <szetszwo@yahoo.com.invalid>
> wrote:
>
> > Hi Senthi
> > The Balancer performance was improved dramatically recently [1].  I am
> not
> > sure if you know about the new conf and parameters; see [2].  If you are
> > interested in more details on how the Balancer works, please see [3].
> > Thanks.
> > 1.
> > https://community.hortonworks.com/content/kbentry/43615/
> hdfs-balancer-1-100x-performance-improvement.html2
> > .
> > https://community.hortonworks.com/content/kbentry/43849/hdfs-balancer-2-
> configurations-cli-options.html3
> > .
> > https://community.hortonworks.com/content/kbentry/44148/
> hdfs-balancer-3-cluster-balancing-algorithm.html
> > Regards,Tsz-Wo
> >
> >     On Thursday, August 11, 2016 6:21 AM, Senthil Kumar <
> > senthilec566@gmail.com> wrote:
> >
> >
> >
> >  Hi Team ,  Pls add your suggestion(s) here , So that i can tune
> parameters
> > to balance cluster which is in bad shape now :( ..
> >
> >
> > --Senthil
> >
> > On Thu, Aug 11, 2016 at 3:51 PM, Senthil Kumar <senthilec566@gmail.com>
> > wrote:
> >
> > > Thanks Lars for your quick response!
> > >
> > > Here is my Cluster Utilization..
> > > DFS Used% : 74.39%
> > > DFS Remaining% : 25.60%
> > >
> > >
> > > Block Pool Used% : 74.39%
> > > DataNodes usages : Min % Median % Max % stdev %
> > > 1.25% 99.72% 99.99% 22.53%
> > > Hadoop Version : *2.4.1*
> > >
> > > Let's take an example :
> > >
> > >  Cluster  Live Nodes          :    1000
> > >  Capacity Used 95-99%      :      700
> > >  Capacity Used 90 -95 %    :      50
> > >  Capacity Used  < 90 %    :      250
> > >
> > > I'm looking for an option to balance the data quickly from the nodes
> > > category 90-95% to < 90% nodes category.. I know there is an option
> like
> > > -include  & -exclude but it's not helping me ( or am i not using it
> > > effectively ??  Pls advise here how to use these options properly if i
> > want
> > > to balance my cluster as described above ) .
> > >
> > > Is there any option like --force-balance ( include two other inputs
> like
> > > force-balance-source-hosts(file) & force-balance-dest-hosts(file) )..
> > > this way i believe we can achieve balancing in urgency mode when you
> have
> > > 90% of nodes hitting  99% disk usage or when we have median 95% and
> above
> > > .. Pls add your thoughts here ..
> > >
> > >
> > > Here is the code that constructs the NW Topology by categorizing like
> > > over-utilized , avg utilized and under-utilized .. Sometimes i could
> see
> > > nodes with 70% of usage also comes under over-utilized ( tried with
> > > threshold 10 - 30 ) . Correct me if anything wrong in my understanding.
> > >
> > > https://github.com/apache/hadoop/tree/release-2.4.1/
> > > hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/
> > > hadoop/hdfs/server/balancer
> > >
> > > */*create network topology and all data node lists: *
> > > *    * overloaded, above-average, below-average, and underloaded*
> > > *    * we alternates the accessing of the given datanodes array either
> > by*
> > > *    * an increasing order or a decreasing order.*
> > > *    */  *
> > > *    long overLoadedBytes = 0L, underLoadedBytes = 0L;*
> > > *    for (DatanodeInfo datanode : DFSUtil.shuffle(datanodes)) {*
> > > *      if (datanode.isDecommissioned() ||
> > > datanode.isDecommissionInProgress()) {*
> > > *        continue; // ignore decommissioning or decommissioned nodes*
> > > *      }*
> > > *      cluster.add(datanode);*
> > > *      BalancerDatanode datanodeS;*
> > > *      final double avg = policy.getAvgUtilization();*
> > > *      if (policy.getUtilization(datanode) > avg) {*
> > > *        datanodeS = new Source(datanode, policy, threshold);*
> > > *        if (isAboveAvgUtilized(datanodeS)) {*
> > > *          this.aboveAvgUtilizedDatanodes.add((Source)datanodeS);*
> > > *        } else {*
> > > *          assert(isOverUtilized(datanodeS)) :*
> > > *            datanodeS.getDisplayName()+ "is not an overUtilized
> node";*
> > > *          this.overUtilizedDatanodes.add((Source)datanodeS);*
> > > *          overLoadedBytes += (long)((datanodeS.utilization-avg*
> > > *              -threshold)*datanodeS.datanode.getCapacity()/100.0);*
> > > *        }*
> > > *      } else {*
> > > *        datanodeS = new BalancerDatanode(datanode, policy,
> threshold);*
> > > *        if ( isBelowOrEqualAvgUtilized(datanodeS)) {*
> > > *          this.belowAvgUtilizedDatanodes.add(datanodeS);*
> > > *        } else {*
> > > *          assert isUnderUtilized(datanodeS) : "isUnderUtilized("*
> > > *              + datanodeS.getDisplayName() + ")=" +
> > > isUnderUtilized(datanodeS)*
> > > *              + ", utilization=" + datanodeS.utilization; *
> > > *          this.underUtilizedDatanodes.add(datanodeS);*
> > > *          underLoadedBytes += (long)((avg-threshold-*
> > > *
> > > datanodeS.utilization)*datanodeS.datanode.getCapacity()/100.0);*
> > > *        }*
> > > *      }*
> > > *      datanodeMap.put(datanode.getDatanodeUuid(), datanodeS);*
> > > *    }*
> > >
> > >
> > > Could someone help me here to understand the balancing policy and what
> > are
> > > the different parameters should i use to balance ( bring down median )
> > > cluster ??
> > >
> > > --Senthil
> > >
> > > On Wed, Aug 10, 2016 at 8:21 PM, Lars Francke <lars.francke@gmail.com>
> > > wrote:
> > >
> > >> Hi Senthil,
> > >>
> > >> I'm not sure I fully understand.
> > >>
> > >> If you're using a threshold of 30 that means you have a range of 60%
> > that
> > >> the balancer would consider to be okay.
> > >>
> > >> Example: The used space divided by your total available space in the
> > >> cluster is 80% Then with a 30% threshold the balancer would try to
> bring
> > >> all nodes within the range of 50-100% utilisation.
> > >>
> > >> The default threshold is 10% and that's a fairly huge range still
> > >> especially on clusters that are almost at capacity. So a threshold of
> 5
> > or
> > >> even lower might work for you.
> > >>
> > >> What is your utilisation in the cluster (used space / available
> space)?
> > >>
> > >> Cheers,
> > >> Lars
> > >>
> > >> On Wed, Aug 10, 2016 at 3:27 PM, Senthil Kumar <
> senthilec566@gmail.com>
> > >> wrote:
> > >>
> > >>> Hi Team ,  We are running big cluster ( 3000 nodes cluster ) , many
> > time
> > >>> we
> > >>> are hitting  Median Increasing to 99.99 % ( 80 % of the DN's ) .
> > >>> Balancer
> > >>> is running all time in cluster ..But still  median is not coming down
> > >>> i.e <
> > >>> 90 % ..
> > >>>
> > >>> Here is how i start balancer ?
> > >>> /apache/hadoop/sbin/start-balancer.sh
> > >>> -Ddfs.balance.bandwidthPerSec=104857600  *-threshold  30*
> > >>>
> > >>> What the recommended value for thershold ??  Is there any way to pass
> > >>> param
> > >>> only to move blocks from Over Utilized ( 98-100%) to under utilized
?
> > >>>
> > >>>
> > >>> Pls advise!
> > >>>
> > >>>
> > >>>
> > >>>
> > >>> Regards,
> > >>> Senthil
> > >>>
> > >>
> > >>
> > >
> >
> >
> >
> >
>

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