Thanks Nicholas for the pointers; the first 2 links are not working. On Thu, Aug 11, 2016 at 10:09 AM Tsz Wo Sze <szets...@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 < > senthilec...@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 <senthilec...@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.fran...@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 <senthilec...@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 > >>> > >> > >> > > > > > >
