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 >>> >> >> >
