Notes for Official-website (Hadoop always-to-be continue.)

1 other services (such as Web apps Proxy Server and MapReduce Job history server) is usually run either on dedicated hard Ware or on shared infrastrucutre, depending upon the load.

2 Control Scripts: Bin/directory of the distribution

setting site-specific values via the etc/hadoop/hadoop-env.sh and etc/hadoop/yarn-env.sh.

3 HDFS daemons is NameNode, Secondarynamenode, and DataNode.

YARN Damones is ResourceManager, NodeManager, and Webappproxy.

4 Hadoop daemons ' process environment: _opts env VARs or _dir or _pid

5 Configuring the Daemons

1. Io.file.buffer.size:Size of read/write buffer used in sequencefiles.
2. Namenode. {Name.dir, Handler.count}: namespace and transactions logs persistently.replicated if comma-delimited more NameNode serv ER threads to handle RPCs
3. Log-aggregation
4. ACL: Set admins on the yarn cluster. ACLs is of for comma-separated-usersspacecomma-separated-groups.

Notes for Official-website (Hadoop always-to-be continue.)