What is HDFS-site XML in Hadoop?

What is HDFS-site XML in Hadoop?

xml file informs Hadoop daemon where NameNode runs in the cluster. It contains the configuration settings for Hadoop Core such as I/O settings that are common to HDFS and MapReduce. The hdfs-site. xml file contains the configuration settings for HDFS daemons; the NameNode, the Secondary NameNode, and the DataNodes.

What is a name node?

The NameNode is the centerpiece of an HDFS file system. It keeps the directory tree of all files in the file system, and tracks where across the cluster the file data is kept. It does not store the data of these files itself.

What is RPC address in Hadoop?

RPC address that handles all clients requests. In the case of HA/Federation where multiple namenodes exist, the name service id is added to the name e.g. dfs. namenode. rpc-address.

What is Hadoop default security?

By default Hadoop runs in non-secure mode in which no actual authentication is required. By configuring Hadoop runs in secure mode, each user and service needs to be authenticated by Kerberos in order to use Hadoop services.

Where is HDFS-site xml located?

These files are all found in the hadoop/conf directory. For setting HDFS you have to configure core-site. xml and hdfs-site. xml.

What yarn stands for?

Yet Another Resource Negotiator

YARN stands for Yet Another Resource Negotiator, but it’s commonly referred to by the acronym alone; the full name was self-deprecating humor on the part of its developers.

Why HDFS is called stateless?

Workers also write results into RAM. You can consider the worker nodes as stateless, since whenever the worker node fails (from power cut for example) it would not have any mechanism which would allow it to recover the execution from the point it has stopped at.

Where is NameNode stored?

The namenode manages the filesystem namespace. It maintains the filesystem tree and the metadata for all the files and directories in the tree. This information is stored in RAM and persisted on the local disk in the form of two files: the namespace image and the edit log.

What is RPC in NameNode?

This alert is triggered if the NameNode operations RPC latency exceeds the configured critical threshold. Typically an increase in the RPC processing time increases the RPC queue length, causing the average queue wait time to increase for NameNode operations.

Is RPC a protocol?

The RPC protocol is a message-passing protocol that implements other non-RPC protocols such as batching and broadcasting remote calls. The RPC protocol also supports callback procedures and the select subroutine on the server side.

How is security done in Hadoop?

Hadoop supports encryption at the disk, file system, database, and application levels. In core Hadoop technology the HFDS has directories called encryption zones. When data is written to Hadoop it is automatically encrypted (with a user-selected algorithm) and assigned to an encryption zone.

Why Kerberos is used in Hadoop?

Hadoop uses Kerberos as the basis for strong authentication and identity propagation for both user and services. Kerberos is a third party authentication mechanism, in which users and services rely on a third party – the Kerberos server – to authenticate each to the other.

What is HDFS used for?

HDFS is a distributed file system that handles large data sets running on commodity hardware. It is used to scale a single Apache Hadoop cluster to hundreds (and even thousands) of nodes. HDFS is one of the major components of Apache Hadoop, the others being MapReduce and YARN.

What is HDFS and yarn?

YARN allows the data stored in HDFS (Hadoop Distributed File System) to be processed and run by various data processing engines such as batch processing, stream processing, interactive processing, graph processing and many more. Thus the efficiency of the system is increased with the use of YARN.

Why is yarn used?

It allows you to use and share code with other developers from around the world. Yarn does this quickly, securely, and reliably so you don’t ever have to worry. Yarn allows you to use other developers’ solutions to different problems, making it easier for you to develop your software.

Which architecture is used by HDFS?

master/slave architecture
HDFS has a master/slave architecture. An HDFS cluster consists of a single NameNode, a master server that manages the file system namespace and regulates access to files by clients.

What is staging in HDFS?

Staging. A client request to create a file does not reach the NameNode immediately. In fact, initially the HDFS client caches the file data into a temporary local file. Application writes are transparently redirected to this temporary local file.

Where is HDFS data stored?

In HDFS data is stored in Blocks, Block is the smallest unit of data that the file system stores. Files are broken into blocks that are distributed across the cluster on the basis of replication factor.

What is metadata in Hadoop?

HDFS metadata represents the structure of HDFS directories and files in a tree. It also includes the various attributes of directories and files, such as ownership, permissions, quotas, and replication factor.

What is RPC latency?

The latency of an RPC is defined as the round-trip time minus the execution time on the target node. The round-trip time is measured from the start of writing the RPC message to the interface until the RPC reply is completely received.

Why is RPC used?

Remote Procedure Call (RPC) protocol is generally used to communicate between processes on different workstations. However, RPC works just as well for communication between different processes on the same workstation. This section explains the Remote Procedure Call (RPC) features.

What is RPC example?

Other examples of the use of RPC in experiments at CERN include: remote monitoring program control, remote FASTBUS access, remote error logging, remote terminal interaction with processors in VMEbus, the submission of operating system commands from embedded microprocessors, and many less general functions.

What is a heartbeat in HDFS?

A ‘heartbeat’ is a signal sent between a DataNode and NameNode. This signal is taken as a sign of vitality. If there is no response to the signal, then it is understood that there are certain health issues/ technical problems with the DataNode or the TaskTracker.

What is Kerberos and how it works?

In our world, Kerberos is the computer network authentication protocol initially developed in the 1980s by Massachusetts Institute of Technology (MIT) computer scientists. The idea behind Kerberos is to authenticate users while preventing passwords from being sent over the internet.

What is Kerberos command?

Kerberos Commands