HDFS

问题 I am little bit confused about Hadoop concepts. What is the difference between Hadoop Chunk size , Split size and Block size ? Thanks in advance. 回答1: Block size & Chunk Size are same. Split size may be different to Block/Chunk size. Map Reduce algorithm does not work on physical blocks of the file. It works on logical input splits. Input split depends on where the record was written. A record may span two mappers. The way HDFS has been set up, it breaks down very large files into large

问题 I'm trying to write unit tests using miniDFSCluster and it's throwing the error below java.lang.UnsatisfiedLinkError: org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z any pointers to resolve this issue? 回答1: With errors like this, I use three steps Find out what it is looking for In this case, *org.apache.hadoop.io.nativeio.NativeIO$Windows.access0* Find out what jar/lib it is in. I don't use the Windows version, but I believe it is in hadoop.dll - you'll have to

问题 I'm trying to write unit tests using miniDFSCluster and it's throwing the error below java.lang.UnsatisfiedLinkError: org.apache.hadoop.io.nativeio.NativeIO$Windows.access0(Ljava/lang/String;I)Z any pointers to resolve this issue? 回答1: With errors like this, I use three steps Find out what it is looking for In this case, *org.apache.hadoop.io.nativeio.NativeIO$Windows.access0* Find out what jar/lib it is in. I don't use the Windows version, but I believe it is in hadoop.dll - you'll have to

问题 I am trying to use the below to list my dirs in hdfs: ubuntu@ubuntu:~$ hadoop fs -ls hdfs://127.0.0.1:50075/ ls: Failed on local exception: com.google.protobuf.InvalidProtocolBufferException: Protocol message end-group tag did not match expected tag.; Host Details : local host is: "ubuntu/127.0.0.1"; destination host is: "ubuntu":50075; Here is my /etc/hosts file 127.0.0.1 ubuntu localhost #127.0.1.1 ubuntu # The following lines are desirable for IPv6 capable hosts ::1 ip6-localhost ip6

问题 I am currently facing issues when trying to join (inner) a huge dataset (654 GB) with a smaller one (535 MB) using Spark DataFrame API . I am broadcasting the smaller dataset to the worker nodes using the broadcast() function. I am unable to do the join between those two datasets. Here is a sample of the errors I got : 19/04/26 19:39:07 INFO executor.CoarseGrainedExecutorBackend: Got assigned task 1315 19/04/26 19:39:07 INFO executor.Executor: Running task 25.1 in stage 13.0 (TID 1315) 19/04

问题 Is there a way to work with HDFS Api using Ruby? As I can understand there is no multilanguage file Api and the only way is to use native Java Api. I tried using JRuby but this solution is to unstable and not very native. Also I looked at HDFS Thrift Api but it's not complete and also lacks many features (like writing to indexed files). Is there a way to work with HDFS using Ruby besides from using JRuby or Thrift Api? 回答1: There are two projects in github that fit what you're asking. ruby

问题 In Big Data the code is pushed towards the data for execution. This makes sense, since data is huge and the code for execution is relatively small. Coming to AWS EMR, the data can be either in HDFS or in S3. In case of S3, the data has to be pulled to the core/task nodes for execution from some other nodes. This might be a bit of overhead when compared to the data in HDFS. Recently, I noticed that when the MR job was executing there was huge latency getting the log files into S3. Sometimes it

问题 In Big Data the code is pushed towards the data for execution. This makes sense, since data is huge and the code for execution is relatively small. Coming to AWS EMR, the data can be either in HDFS or in S3. In case of S3, the data has to be pulled to the core/task nodes for execution from some other nodes. This might be a bit of overhead when compared to the data in HDFS. Recently, I noticed that when the MR job was executing there was huge latency getting the log files into S3. Sometimes it

问题 I am using Hadoop 1.0.3 in a Pseudo-Distributed mode. And my conf/core-site.xml is set as follows: <configuration> <property> <name>fs.default.name</name> <value>hdfs://localhost:9000</value> </property> <property> <name>mapred.child.tmp</name> <value>/home/administrator/hadoop/temp</value> </property> </configuration> So I believed that my default filesystem is set to HDFS. However, when I run the following code: Configuration conf = new Configuration(); FileSystem fs = FileSystem.get(conf);

问题 All my nodes are up and running when we see using jps command, but still I am unable to connect to hdfs filesystem. Whenever I click on Browse the filesystem on the Hadoop Namenode localhost:8020 page, the error which i get is Connection Refused . Also I have tried formatting and restarting the namenode but still the error persist. Can anyone please help me solving this issue. 回答1: Check whether all your services are running JobTracker, Jps, NameNode. DataNode, TaskTracker by running jps