Hi Sidharth,
Thanks a lot for the clarification. May you suggest parameters that can improve the re-replication in case of failure. Regards Om From: Sidharth Kumar [mailto:[email protected]] Sent: 29 June 2017 16:06 To: omprakash <[email protected]> Cc: Arpit Agarwal <[email protected]>; [email protected] <[email protected]>; Ravi Prakash <[email protected]> Subject: RE: Lots of warning messages and exception in namenode logs Hi, No, as there will be no copy exists of that file. You can increase the replication factor to 3 so that there will be 3 copies created and even if 2 data nodes goes down you will still have one copy available which will be again replicated to 3 by the namenode in due course of time. Warm Regards Sidharth Kumar | Mob: +91 8197 555 599/7892 192 367 | LinkedIn:www.linkedin.com/in/sidharthkumar2792 <http://www.linkedin.com/in/sidharthkumar2792> On 29-Jun-2017 3:45 PM, "omprakash" <[email protected] <mailto:[email protected]> > wrote: Hi Ravi, I have 5 nodes in Hadoop cluster and all have same configurations. After setting dfs.replication=2 , I did a clean start of hdfs. As per your suggestion, I added 2 more datanodes and clean all the data and metadata. The performance of the cluster has dramatically improved. I can see through logs that the files are randomly replicated to four datanodes (2 replica of each file). But here my problem arise. I want redundant datanodes such that if any two of the datanodes goes down I still be able to get files from other two. In above case suppose file block-xyz get stored on datanode1 and datanode2, and some day these two datanodes goes down , will I be able to access the block-xyz? This is what I am worried about. Regards Om From: Ravi Prakash [mailto: <mailto:[email protected]> [email protected]] Sent: 27 June 2017 22:36 To: omprakash < <mailto:[email protected]> [email protected]> Cc: Arpit Agarwal < <mailto:[email protected]> [email protected]>; user < <mailto:[email protected]> [email protected]> Subject: Re: Lots of warning messages and exception in namenode logs Hi Omprakash! This is *not* ok. Please go through the datanode logs of the inactive datanode and figure out why its inactive. If you set dfs.replication to 2, atleast as many datanodes (and ideally a LOT more datanodes) should be active and participating in the cluster. Do you have the hdfs-site.xml you posted to the mailing list on all the nodes (including the Namenode)? Was the file containing block blk_1074074104_337394 created when you had the cluster misconfigured to dfs.replication=3 ? You can determine which file the block belongs to using this command: hdfs fsck -blockId blk_1074074104 Once you have the file, you can set its replication using hdfs dfs -setrep 2 <Filename> I'm guessing that you probably have a lot of files with this replication, in which case you should set it on / (This would overwrite the replication on all the files) If the data on this cluster is important I would be very worried about the condition its in. HTH Ravi On Mon, Jun 26, 2017 at 11:22 PM, omprakash <[email protected] <mailto:[email protected]> > wrote: Hi all, I started the HDFS in DEBUG mode. After examining the logs I found below logs which read that the replication factor required is 3 (as against the specified dfs.replication=2). DEBUG BlockStateChange: BLOCK* NameSystem.UnderReplicationBlock.add: blk_1074074104_337394 has only 1 replicas and need 3 replicas so is added to neededReplications at priority level 0 P.S : I have 1 datanode active out of 2. I can also see from Namenode UI that the no. of under replicated blocks are growing. Any idea? Or this is OK. regards From: omprakash [mailto: <mailto:[email protected]> [email protected]] Sent: 23 June 2017 11:02 To: 'Ravi Prakash' < <mailto:[email protected]> [email protected]>; 'Arpit Agarwal' < <mailto:[email protected]> [email protected]> Cc: 'user' < <mailto:[email protected]> [email protected]> Subject: RE: Lots of warning messages and exception in namenode logs Hi Arpit, I will enable the settings as suggested and will post the results. I am just curious about setting Namenode RPC service port. As I have checked the hdfs-site.xml properties, dfs.namenode.rpc-address is already set which will be default value to RPC service port also. Does specifying any other port have advantage over default one? Regarding JvmPauseMonitor Error, there are 5-6 instances of this error in namenode logs. Here is one of them. How to identify the size of heap In such cases as I have 4GB of RAM on the namenode VM.? @Ravi Since the file size are very small thus I have only configured a VM with 20 GB space. The additional disk is simple SATA disk not SSD. As I can see from Namenode UI there are more than 50% of block under replicated. I have now 400K blocks out of which 200K are under-replicated. I will post the results again after changing the value of <http://dfs.namenode.replication.work> dfs.namenode.replication.work.multiplier.per.iteration Thanks Om Prakash From: Ravi Prakash [ <mailto:[email protected]> mailto:[email protected]] Sent: 22 June 2017 23:04 To: Arpit Agarwal < <mailto:[email protected]> [email protected]> Cc: omprakash < <mailto:[email protected]> [email protected]>; user < <mailto:[email protected]> [email protected]> Subject: Re: Lots of warning messages and exception in namenode logs Hi Omprakash! How big are your disks? Just 20Gb? Just out of curiosity, are these SSDs? In addition to Arpit's reply, I'm also concerned with the number of under-replicated blocks you have: Under replicated blocks: 141863 When there are fewer replicas for a block than there are supposed to be (in your case e.g. when there's 1 replica when there ought to be 2), the namenode will order the datanodes to create more replicas. The rate at which it does this is controlled by dfs.namenode.replication.work <http://dfs.namenode.replication.work> .multiplier.per.iteration . Given you have only 2 datanodes, you'll only be re-replicating 4 blocks every 3 seconds. So, it will take quite a while to re-replicate all the blocks. Also, please know that you want files to be much bigger than 1kb. Ideally you'd have a couple of blocks (blocks=128Mb) for each file. You should append to files when they are this small. Please do let us know how things turn out. Cheers, Ravi On Wed, Jun 21, 2017 at 11:23 PM, Arpit Agarwal <[email protected] <mailto:[email protected]> > wrote: Hi Omprakash, Your description suggests DataNodes cannot send timely reports to the NameNode. You can check it by looking for ‘stale’ DataNodes in the NN web UI when this situation is occurring. A few ideas: * Try increasing the NameNode RPC handler count a bit (set dfs.namenode.handler.count to 20 in hdfs-site.xml). * Enable the NameNode service RPC port. This requires downtime and reformatting the ZKFC znode. * Search for JvmPauseMonitor messages in your service logs. If you see any, try increasing JVM heap for that service. * Enable debug logging as suggested here: 2017-06-21 12:11:30,626 WARN org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy: Failed to place enough replicas, still in need of 1 to reach 2 (unavailableStorages=[], storagePolicy=BlockStoragePolicy{HOT:7, storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]}, newBlock=true) For more information, please enable DEBUG log level on org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy and <http://org.apache.hadoop.net/> org.apache.hadoop.net.NetworkTopology From: omprakash < <mailto:[email protected]> [email protected]> Date: Wednesday, June 21, 2017 at 9:23 PM To: 'Ravi Prakash' < <mailto:[email protected]> [email protected]> Cc: 'user' < <mailto:[email protected]> [email protected]> Subject: RE: Lots of warning messages and exception in namenode logs Hi Ravi, Pasting below my core-site and hdfs-site configurations. I have kept bare minimal configurations for my cluster. The cluster started fine and I was able to put couple of 100K files on hdfs but then when I checked the logs there were errors/Exceptions. After restart of datanodes they work well for few thousand files but same problem again. No idea what is wrong. PS: I am pumping 1 file per second to hdfs with aprox size 1KB I thought it may be due to space quota on datanodes but here is the output of hdfs dfs -report. Looks fine to me $ hdfs dfsadmin -report Configured Capacity: 42005069824 (39.12 GB) Present Capacity: 38085839568 (35.47 GB) DFS Remaining: 34949058560 (32.55 GB) DFS Used: <tel:(313)%20678-1008> 3136781008 (2.92 GB) DFS Used%: 8.24% Under replicated blocks: 141863 Blocks with corrupt replicas: 0 Missing blocks: 0 Missing blocks (with replication factor 1): 0 Pending deletion blocks: 0 ------------------------------------------------- Live datanodes (2): Name: <http://192.168.9.174:50010> 192.168.9.174:50010 (node5) Hostname: node5 Decommission Status : Normal Configured Capacity: 21002534912 (19.56 GB) DFS Used: 1764211024 (1.64 GB) Non DFS Used: 811509424 (773.92 MB) DFS Remaining: <tel:(706)%20791-3216> 17067913216 (15.90 GB) DFS Used%: 8.40% DFS Remaining%: 81.27% Configured Cache Capacity: 0 (0 B) Cache Used: 0 (0 B) Cache Remaining: 0 (0 B) Cache Used%: 100.00% Cache Remaining%: 0.00% Xceivers: 2 Last contact: Wed Jun 21 14:38:17 IST 2017 Name: <http://192.168.9.225:50010> 192.168.9.225:50010 (node4) Hostname: node5 Decommission Status : Normal Configured Capacity: 21002534912 (19.56 GB) DFS Used: 1372569984 (1.28 GB) Non DFS Used: 658353792 (627.86 MB) DFS Remaining: 17881145344 (16.65 GB) DFS Used%: 6.54% DFS Remaining%: 85.14% Configured Cache Capacity: 0 (0 B) Cache Used: 0 (0 B) Cache Remaining: 0 (0 B) Cache Used%: 100.00% Cache Remaining%: 0.00% Xceivers: 1 Last contact: Wed Jun 21 14:38:19 IST 2017 core-site.xml <?xml version="1.0" encoding="UTF-8"?> <?xml-stylesheet type="text/xsl" href="configuration.xsl"?> <configuration> <property> <name>fs.defaultFS</name> <value>hdfs://hdfsCluster</value> </property> <property> <name>dfs.journalnode.edits.dir</name> <value>/mnt/hadoopData/hadoop/journal/node/local/data</value> </property> </configuration> hdfs-site.xml <?xml version="1.0" encoding="UTF-8"?> <?xml-stylesheet type="text/xsl" href="configuration.xsl"?> <configuration> <property> <name>dfs.replication</name> <value>2</value> </property> <property> <name>dfs.name.dir</name> <value> <file:///mnt/hadoopData/hadoop/hdfs/namenode%3c/value> file:///mnt/hadoopData/hadoop/hdfs/namenode</value> </property> <property> <name>dfs.data.dir</name> <value> <file:///mnt/hadoopData/hadoop/hdfs/datanode%3c/value> file:///mnt/hadoopData/hadoop/hdfs/datanode</value> </property> <property> <name>dfs.nameservices</name> <value>hdfsCluster</value> </property> <property> <name>dfs.ha.namenodes.hdfsCluster</name> <value>nn1,nn2</value> </property> <property> <name>dfs.namenode.rpc-address.hdfsCluster.nn1</name> <value>node1:8020</value> </property> <property> <name>dfs.namenode.rpc-address.hdfsCluster.nn2</name> <value>node22:8020</value> </property> <property> <name>dfs.namenode.http-address.hdfsCluster.nn1</name> <value>node1:50070</value> </property> <property> <name>dfs.namenode.http-address.hdfsCluster.nn2</name> <value>node2:50070</value> </property> <property> <name>dfs.namenode.shared.edits.dir</name> <value>qjournal://node1:8485;node2:8485;node3:8485;node4:8485;node5:8485/hdfsCluster</value> </property> <property> <name>dfs.client.failover.proxy.provider.hdfsCluster</name> <value>org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider</value> </property> <property> <name>ha.zookeeper.quorum</name> <value>node1:2181,node2:2181,node3:2181,node4:2181,node5:2181</value> </property> <property> <name>dfs.ha.fencing.methods</name> <value>sshfence</value> </property> <property> <name>dfs.ha.fencing.ssh.private-key-files</name> <value>/home/hadoop/.ssh/id_rsa</value> </property> <property> <name>dfs.ha.automatic-failover.enabled</name> <value>true</value> </property> </configuration> From: Ravi Prakash [mailto: <mailto:[email protected]> [email protected]] Sent: 22 June 2017 02:38 To: omprakash < <mailto:[email protected]> [email protected]> Cc: user < <mailto:[email protected]> [email protected]> Subject: Re: Lots of warning messages and exception in namenode logs Hi Omprakash! What is your default replication set to? What kind of disks do your datanodes have? Were you able to start a cluster with a simple configuration before you started tuning it? HDFS tries to create the default number of replicas for a block on different datanodes. The Namenode tries to give a list of datanodes that the client can write replicas of the block to. If the Namenode is not able to construct a list with adequate number of datanodes, you will see the message you are seeing. This may mean that datanodes are unhealthy (failed disks), or full (disks have no more space), being decomissioned ( HDFS will not write replicas on decomissioning datanodes) or misconfigured ( I'd suggest turning on storage classes only after a simple configuration works). When a client that was trying to write a file was killed (e.g. if you killed your MR job), after some time (hard limit expiring) the Namenode will try to recover the file. In your case the namenode is also not able to find enough datanodes for recovering the files. HTH Ravi On Tue, Jun 20, 2017 at 11:50 PM, omprakash < <mailto:[email protected]> [email protected]> wrote: Hi, I am receiving lots of warning messages in namenodes logs on ACTIVE NN in my HA Hadoop setup. Below are the logs “2017-06-21 12:11:26,523 WARN org.apache.hadoop.hdfs.protocol.BlockStoragePolicy: Failed to place enough replicas: expected size is 1 but only 0 storage types can be selected (replication=2, selected=[], unavailable=[DISK], removed=[DISK], policy=BlockStoragePolicy{HOT:7, storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]}) 2017-06-21 12:11:26,523 WARN org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy: Failed to place enough replicas, still in need of 1 to reach 2 (unavailableStorages=[DISK], storagePolicy=BlockStoragePolicy{HOT:7, storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]}, newBlock=true) All required storage types are unavailable: unavailableStorages=[DISK], storagePolicy=BlockStoragePolicy{HOT:7, storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]} 2017-06-21 12:11:26,523 INFO org.apache.hadoop.hdfs.StateChange: BLOCK* allocate blk_1073894332_153508, replicas= <http://192.168.9.174:50010> 192.168.9.174:50010 for /36962._COPYING_ 2017-06-21 12:11:26,810 INFO org.apache.hadoop.hdfs.StateChange: DIR* completeFile: /36962._COPYING_ is closed by DFSClient_NONMAPREDUCE_146762699_1 2017-06-21 12:11:30,626 WARN org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy: Failed to place enough replicas, still in need of 1 to reach 2 (unavailableStorages=[], storagePolicy=BlockStoragePolicy{HOT:7, storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]}, newBlock=true) For more information, please enable DEBUG log level on org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy and <http://org.apache.hadoop.net> org.apache.hadoop.net.NetworkTopology 2017-06-21 12:11:30,626 WARN org.apache.hadoop.hdfs.protocol.BlockStoragePolicy: Failed to place enough replicas: expected size is 1 but only 0 storage types can be selected (replication=2, selected=[], unavailable=[DISK], removed=[DISK], policy=BlockStoragePolicy{HOT:7, storageTypes=[DISK], creationFallbacks=[], replicationFallbacks=[ARCHIVE]})” I am also encountering exceptions in active namenode related to LeaseManager 2017-06-21 12:13:16,706 INFO org.apache.hadoop.hdfs.server.namenode.LeaseManager: [Lease. Holder: DFSClient_NONMAPREDUCE_409197282_362092, pending creates: 1] has expired hard limit 2017-06-21 12:13:16,706 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Recovering [Lease. Holder: DFSClient_NONMAPREDUCE_409197282_362092, pending creates: 1], src=/user/hadoop/ <tel:(210)%20620-1707> 2106201707/02d5adda-d90f-47cb-85d5-999a079f4d79 2017-06-21 12:13:16,706 WARN org.apache.hadoop.hdfs.StateChange: DIR* NameSystem.internalReleaseLease: Failed to release lease for file /user/hadoop/ <tel:(210)%20620-1707> 2106201707/02d5adda-d90f-47cb-85d5-999a079f4d79. Committed blocks are waiting to be minimally replicated. Try again later. 2017-06-21 12:13:16,706 ERROR org.apache.hadoop.hdfs.server.namenode.LeaseManager: Cannot release the path /user/hadoop/ <tel:(210)%20620-1707> 2106201707/02d5adda-d90f-47cb-85d5-999a079f4d79 in the lease [Lease. Holder: DFSClient_NONMAPREDUCE_409197282_362092, pending creates: 1] org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException: DIR* NameSystem.internalReleaseLease: Failed to release lease for file /user/hadoop/ <tel:(210)%20620-1707> 2106201707/02d5adda-d90f-47cb-85d5-999a079f4d79. Committed blocks are waiting to be minimally replicated. Try again later. at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.internalReleaseLease(FSNamesystem.java:3200) at org.apache.hadoop.hdfs.server.namenode.LeaseManager.checkLeases(LeaseManager.java:383) at org.apache.hadoop.hdfs.server.namenode.LeaseManager$Monitor.run(LeaseManager.java:329) at java.lang.Thread.run(Thread.java:745) I have checked the two datanodes. Both are running and have enough space for new data. PS: I have 2 Namenode and 2 datanodes in Hadoop HA setup. The HA is setuped using Qourom Journal Manager and Zookeeper server. Any idea why these errors? Regards Omprakash Paliwal HPC-Medical and Bioinformatics Applications Group Centre for Development of Advanced Computing (C-DAC) Pune University campus, PUNE-411007 Maharashtra, India email: <mailto:[email protected]> [email protected] Contact : <tel:+91%2020%202570%204231> +91-20-25704231 ------------------------------------------------------------------------------------------------------------------------------- [ C-DAC is on Social-Media too. Kindly follow us at: Facebook: <https://www.facebook.com/CDACINDIA> https://www.facebook.com/CDACINDIA & Twitter: @cdacindia ] This e-mail is for the sole use of the intended recipient(s) and may contain confidential and privileged information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies and the original message. 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