Can we run the NameNode and DataNode on the same machine?

Can we run the NameNode and DataNode on the same machine?

Yes, you can have a DataNode on the same machine as the NameNode. However, it is recommended only when you have a small cluster (a few machines, for example, fewer than 10). When using the HDFS, the name node keeps track of all the data in the Hadoop file system.

What is the difference between a NameNode and a DataNode?

The main difference between NameNode and DataNode in Hadoop is that the NameNode is the master node in HDFS that manages the file system metadata while the DataNode is a slave node in HDFS that stores the actual data as instructed by the NameNode. In brief, NameNode controls and manages a single or multiple data nodes.

What is difference between backup node and secondary NameNode?

Yes, Secondary name node is Checkpoint name node – which only merges fsimage and edit logs in an interval. Backup namenode is extension to Secondary namenode – that additionaly, receives updates on real time of fs metadata from namenode – making sure that on-memory and on-disk image is up-to-date.

How do I backup my Hadoop data?

Hadoop backup: what parts to backup and how to do it?

1. Configuration files.
2. Ambari server meta info.
3. NameNode metadata.
4. Ambari repository database. Backup with Point In Time Recovery (PITR) capability. Backup with no PITR capability.
5. Hive repository database. Backup with Point In Time Recovery (PITR) capability.

Which machine is NameNode?

The NameNode and DataNode are pieces of software designed to run on commodity machines. These machines typically run a GNU/Linux operating system ( OS ). HDFS is built using the Java language; any machine that supports Java can run the NameNode or the DataNode software.

How many DataNodes can be run on a single Hadoop?

A good rule of thumb is to assume 1GB of NameNode memory for every 1 million blocks stored in the distributed file system. With 100 DataNodes in a cluster, 64GB of RAM on the NameNode provides plenty of room to grow the cluster.”

What is the DataNode?

The DataNodes are responsible for serving read and write requests from the file system’s clients. The DataNodes also perform block creation, deletion, and replication upon instruction from the NameNode. The NameNode and DataNode are pieces of software designed to run on commodity machines.

What is DataNode and name node?

DataNode is responsible for storing the actual data in HDFS. When a DataNode is down, it does not affect the availability of data or the cluster. NameNode will arrange for replication for the blocks managed by the DataNode that is not available. DataNode is usually configured with a lot of hard disk space.

What is DataNode?

DataNodes are the slave nodes in HDFS. The actual data is stored on DataNodes. A functional filesystem has more than one DataNode, with data replicated across them. Local and remote client applications can talk directly to a DataNode, once the NameNode has provided the location of the data.

What is difference between NameNode and secondary NameNode?

Name node is the one which stores the information of HDFS filesystem in a file called FSimage. Any changes that you make in your HDFS are never logged directly into FSimage. instead, they are logged into a separate temporary file. This temporary file which stores the intermediate data is called Secondary name node.

What is backup in Hadoop?

Data in an HDFS storage location is backed up to HDFS. This backup guards against accidental deletion or corruption of data. It does not prevent data loss in the case of a catastrophic failure of the entire Hadoop cluster. To prevent data loss, you must have a backup and disaster recovery plan for your Hadoop cluster.

What is right about Cloudera backup and disaster recovery?

If you have the raw data in HDFS (which most do, and which you should!), the most straightforward way to have a hot-warm disaster recovery setup is to use our Backup and Disaster Recovery tool. It allows you to set up regular incremental updates between two clusters.

How is DataNode and NameNode used in Hadoop?

DataNode in Hadoop. Though Namenode in Hadoop acts as an arbitrator and repository for all metadata but it doesn’t store actual data of the file. HDFS is designed in such a way that user data never flows through the NameNode. Actual data of the file is stored in Datanodes in Hadoop cluster.

Where are data blocks stored in a NameNode?

The NameNode returns list of DataNodes where the data blocks are stored for the given file. Data blocks of the files are stored in a set of DataNodes in Hadoop cluster. Client application gets the list of DataNodes where data blocks of a particular file are stored from NameNode.

Where does the data go in HDFS NameNode?

Though Namenode in Hadoop acts as an arbitrator and repository for all metadata but it doesn’t store actual data of the file. HDFS is designed in such a way that user data never flows through the NameNode. Actual data of the file is stored in Datanodes in Hadoop cluster.

How does the NameNode work in a client?

Any client application that needs to process any existing file or want to copy a new file has to talk to Namenode. The Namenode returns a list of Datanodes where blocks of existing files are residing or blocks of a new file can be written and replicated.