Note: This is post is part of the HDPCA exam objective series When you install the HDP cluster for the first time, you can specify the services that you want to configure in the ambari server. But you can always add or remove any service later on using the ambari server Web UI. In this […]
Archives for July 2018
HDPCA Exam Objective – Decommission a node (NodeManager)
Note: This is post is part of the HDPCA exam objective series What is a NodeManager A NodeManager agent is deployed on each of the processing nodes in the cluster. It is the counterpart to the ResourceManager at the node level. It communicates with the ResourceManager to update the node state and receive any job […]
HDPCA Exam Objective – Decommission a node (datanode)
Note: This is post is part of the HDPCA exam objective series Sometimes we have to remove a cluster node from a live cluster for maintenance or if the node is dying or simply to reduce the size of the cluster. Decommissioning is a process that supports removing a component from the cluster. You must […]
18 Practical tcpdump Command Examples – A Network Sniffer Tool Primer
What is tcpdump tcpdump is a most powerful and widely used command-line packets sniffer or package analyzer tool which is used to capture or filter TCP/IP packets that received or transferred over a network on a specific interface. It is available under most of the Linux/Unix based operating systems. tcpdump also gives us an option […]
Linux OS Service ‘setroubleshoot’
SELinux (Security Enhanced Linux) provides mandatory access control to the Linux operating system. SELinux is quite pervasive, even if only in PERMISSIVE mode. This can expose latent bugs in non-SELinux components that are not visible unless SELinux is running. Frustrated users have developed the perception that SELinux is difficult to use. The setroubleshoot service is […]
Linux OS Service ‘psacct’
The psacct service is responsible for starting and stopping process accounting at system boot time and at system shutdown. This service is a wrapper that invokes the action accounting control program. Service Control To obtain the psacct service, install the psacct RPM package: # yum install psacct To manage the psacct service for automated service […]
Linux OS Service ‘NetworkManagerDispatcher’
The NetworkManager daemon attempts to keep an active network connection available at all times. The NetworkManager facility offers a tool called NetworkManagerDispatcher which executes commands in /etc/NetworkManager/dispatcher.d according to the changing state of the network interfaces. All scripts in this directory are invoked for every state change of any network interface; the scripts must decide […]
Linux OS Service ‘yum-updatesd’
The yum-updatesd daemon regularly checks the yum repository and provides notification of updates available for your system. Notifications can be made via syslog, email or dbus, a communication method used between applications. When configured to connect a yum repository, the daemon calls the “yum update” command to update packages on the system. The yum-updatesd service […]
Linux OS Service ‘acpid’
The acpid daemon supports the Advanced Configuration and Power Interface (ACPI) to allow intelligent power management on your system and to query battery and configuration status. It listens on a file (/proc/acpi/event) and when an event occurs, executes programs to handle the event. Rules are defined by simple configuration files. acpid will look in a […]
Linux OS Service ‘rpcidmapd’
This executes rpcidmapd, with NFS service. The rpcidmapd maps usernames to UID and GID numbers. Service Control To manage the rpcidmapd service on demand, use the service tool or run the /etc/init.d/rpcidmapd script directly: # /sbin/service rpcidmapd Usage: /etc/init.d/rpcidmapd {start|stop|restart|condstart|condrestart|status} # /etc/init.d/rpcidmapd Usage: /etc/init.d/rpcidmapd {start|stop|restart|condstart|condrestart|status} The available commands are: Command Description start Start the rpcidmapd […]