rhel cluster basics 3

Cluster Administration Tools

Conga

Conga is an integrated set ofsoftware components that providescentralized configuration andmanagement of Red Hat clustersand storage.

Conga: Features

• One Web interface for managing cluster and storage

• Automated Deployment of Cluster Data and Supporting Packages

• Easy Integration with Existing Clusters

• No Need to Re-Authenticate

• Integration of Cluster Status and Logs

• Fine-Grained Control over User Permissions

Conga: Primary Components

• The primary components in Conga are luci andricci, which are separately installable.

• luci is a server that runs on one computer andcommunicates with multiple clusters andcomputers via ricci.

• ricci is an agent that runs on each computer(either a cluster member or a standalonecomputer) managed by Conga.

Luci

luci is accessible through a Web browser and provides threemajor functions that are accessible through the following tabs:• homebase — Provides tools for adding and deleting

computers, adding and deleting users, and configuring userprivileges. Only a system administrator is allowed to accessthis tab.

• cluster — Provides tools for creating and configuring clusters.Each instance of luci lists clusters that have been set up withthat luci. A system administrator can administer all clusterslisted on this tab. Other users can administer only clustersthat the user has permission to manage (granted by anadministrator).

• storage — Provides tools for remote administration ofstorage. With the tools on this tab, you can manage storageon computers whether they belong to a cluster or not.

Luci

• To administer a cluster or storage, an administratoradds (or registers) a cluster or a computer to a luciserver. When a cluster or a computer is registeredwith luci, the FQDN hostname or IP address of eachcomputer is stored in a luci database.

• Each luci instance has one user at initial installation— admin. Only the admin user may add systems toa luci server. Also, the admin user can createadditional user accounts and determine whichusers are allowed to access clusters and computersregistered in the luci database.

Luci: homebase tab

Luci: cluster tab

Luci: storage tab

Cluster Administration GUI

• The system-config-cluster cluster administrationgraphical user interface (GUI) available with RedHat Cluster Suite.

• The GUI is for use with the cluster infrastructureand the high-availability service managementcomponents.

Cluster Administration GUI

• The GUI consists of two major functions:

– Cluster Configuration Tool

– Cluster Status Tool

• The Cluster Configuration Tool provides thecapability to create, edit, and propagate thecluster configuration file

(/etc/cluster/cluster.conf).

• The Cluster Status Tool provides the capability tomanage high-availability services.

Cluster Configuration Tool

Cluster Configuration Tool: components

Cluster Nodes — Displays cluster nodes. Using configurationbuttons you can add nodes, delete nodes, edit nodeproperties, and configure fencing methods for each node.

Fence Devices — Displays fence devices. Using configurationbuttons you can add fence devices, delete fence devices, andedit fence-device properties. Fence devices must be definedbefore you can configure fencing (with the Manage FencingFor This Node button) for each node.

Managed Resources — Displays failover domains, resources,and services.

Cluster Configuration Tool: components

Managed Resources —Failover Domains — For configuring one or more subsetsof cluster nodes used to run a high-availability service inthe event of a node failure.Resources — For configuring shared resources to be usedby high-availability services. Shared resources consist of filesystems, IP addresses, NFS mounts and exports, and user-created scripts that are available to any high-availabilityservice in the cluster.Services — For creating and configuring high-availabilityservices. A service is configured by assigning resources(shared or private), assigning a failover domain, anddefining a recovery policy for the service.

Cluster Status Tool

Command Line Administration Tools

• In addition to Conga and the system-config-cluster Cluster Administration GUI, commandline tools are available for administering thecluster infrastructure and the high-availabilityservice management components.

• The command line tools are used by the ClusterAdministration GUI and init scripts supplied byRed Hat.

Command Line Tool Used With Purpose

ccs_tool — Cluster Configuration System Tool

Cluster Infrastructure

ccs_tool is a program for making online updatesto the cluster configuration file. It provides thecapability to create and modify clusterinfrastructure components (for example,creating a cluster, adding and removing a node).

cman_tool —Cluster Management Tool


cman_tool is a program that manages theCMAN cluster manager. It provides thecapability to join a cluster, leave a cluster, kill anode, or change the expected quorum votes ofa node in a cluster.

fence_tool — Fence Tool


fence_tool is a program used to join or leave thedefault fence domain. Specifically, it starts thefence daemon (fenced) to join the domain andkills fenced to leave the domain.

Command Line Tools

Command Line Tool Used With Purpose

clustat — Cluster Status Utility

High-availabilityService ManagementComponents

The clustat command displays the status of thecluster. It shows membership information,quorum view, and the state of all configureduser services.

clusvcadm — Cluster User Service Administration Utility

High-availabilityService ManagementComponents

The clusvcadm command allows you to enable,disable, relocate, and restart high-availabilityservices in a cluster.

Command Line Tools

Linux Virtual Server Administration GUI

Piranha Configuration Tool

• The Piranha Configuration Tool is a Web-browsergraphical user interface (GUI) that provides astructured approach to creating the configurationfile for LVS — /etc/sysconfig/ha/lvs.cf.

• To access the Piranha Configuration Tool you needthe piranha-gui service running on the active LVSrouter.

• You can access the Piranha Configuration Toollocally (URL: http://localhost:3636) or remotely(hostname or the real IP address :3636) with aWeb browser.

• If you are accessing the Piranha Configuration Toolremotely, you need an ssh connection to the activeLVS router as the root user.

Piranha Configuration Tool: The Welcome panel

Piranha Configuration Tool: CONTROL/MONITORING

Piranha Configuration Tool: CONTROL/MONITORING

Logging in to the welcome page provides access to the four mainscreens or panels: CONTROL/MONITORING, GLOBAL SETTINGS,REDUNDANCY, and VIRTUAL SERVERS.

The CONTROL/MONITORING Panel displays runtime status. Itdisplays the status of the pulse daemon, the LVS routing table, andthe LVS-spawned nanny processes.Auto update Enables the status display to be updated automaticallyat a user-configurable interval set in the Update frequency inseconds text box (the default value is 10 seconds).Update information now Provides manual update of the statusinformation.CHANGE PASSWORD Clicking this button takes you to a help screenwith information on how to change the administrative password forthe Piranha Configuration Tool.

Piranha Configuration Tool: GLOBAL SETTINGS

The GLOBAL SETTINGS panel is where the LVS administrator definesthe networking details for the primary LVS router's public and privatenetwork interfaces.

The top half of this panel sets up the primary LVS router's public andprivate network interfaces.

Primary server public IP The publicly routable real IP address for theprimary LVS node.

Primary server private IP The real IP address for an alternativenetwork interface on the primary LVS node. This address is usedsolely as an alternative heartbeat channel for the backup router.

Use network type Selects select NAT routing.


The next three fields are specifically for the NAT router'svirtual network interface connected the private networkwith the real servers.

NAT Router IP The private floating IP in this text field. Thisfloating IP should be used as the gateway for the realservers.

NAT Router netmask If the NAT router's floating IP needs aparticular netmask, select it from drop-down list.

NAT Router device Defines the device name of the networkinterface for the floating IP address, such as eth1:1.

Piranha Configuration Tool: REDUNDANCY

The REDUNDANCY panel allows you to configure of thebackup LVS router node and set various heartbeatmonitoring options.

Redundant server public IP The public real IP address forthe backup LVS router.

Redundant server private IP The backup router's privatereal IP address.The rest of the panel is for configuring the heartbeatchannel, which is used by the backup node to monitor theprimary node for failure.


Heartbeat Interval (seconds) Sets the number of secondsbetween heartbeats — the interval that the backup nodewill check the functional status of the primary LVS node.

Assume dead after (seconds) If the primary LVS nodedoes not respond after this number of seconds, then thebackup LVS router node will initiate failover.Heartbeat runs on port Sets the port at which theheartbeat communicates with the primary LVS node. Thedefault is set to 539 if this field is left blank.


Redundant server public IP : The public real IP address forthe backup LVS router.

Redundant server private IP : The backup router's privatereal IP address.

The rest of the panel is for configuring the heartbeatchannel, which is used by the backup node to monitor theprimary node for failure.

Heartbeat Interval (seconds) : Sets the number of secondsbetween heartbeats — the interval that the backup nodewill check the functional status of the primary LVS node.


Assume dead after (seconds) : If the primary LVS nodedoes not respond after this number of seconds, then thebackup LVS router node will initiate failover.

Heartbeat runs on port : Sets the port at which theheartbeat communicates with the primary LVS node. Thedefault is set to 539 if this field is left blank.

VIRTUAL SERVERS

VIRTUAL SERVERS Panel

• Each server displayed in the VIRTUAL SERVERSpanel can be configured on subsequent screens orsubsections.

• To add a service, click the ADD button. To remove aservice, select it by clicking the radio button next tothe virtual server and click the DELETE button.

• To enable or disable a virtual server in the tableclick its radio button and click the (DE)ACTIVATEbutton.

• After adding a virtual server, you can configure it byclicking the radio button to its left and clicking theEDIT button to display the VIRTUAL SERVERsubsection.

VIRTUAL SERVERS Subsection


• Name: A descriptive name to identify the virtualserver. This name is not the hostname for themachine, so make it descriptive and easilyidentifiable. You can even reference the protocolused by the virtual server, such as HTTP.

• Application port: The port number through whichthe service application will listen.

• Protocol: Provides a choice of UDP or TCP, in adrop-down menu.

• Virtual IP Address: The virtual server's floating IPaddress.


• Virtual IP: Network Mask The netmask for thisvirtual server, in the drop-down menu.

• Firewall Mark: For entering a firewall mark integervalue when bundling multi-port protocols orcreating a multi-port virtual server for separate, butrelated protocols.

• Device: The name of the network device to whichyou want the floating IP address defined in theVirtual IP Address field to bind.

• Re-entry Time: An integer value that defines thenumber of seconds before the active LVS routerattempts to use a real server after the real serverfailed.


• Service Timeout: An integer value that defines thenumber of seconds before a real server isconsidered dead and not available.

• Quiesce server: When the Quiesce server radiobutton is selected, anytime a new real server nodecomes online, the least-connections table is resetto zero so the active LVS router routes requests as ifall the real servers were freshly added to thecluster. This option prevents the a new server frombecoming bogged down with a high number ofconnections upon entering the cluster.


• Load monitoring tool: The LVS router can monitor theload on the various real servers by using either rup orruptime. If you select rup from the drop-down menu,each real server must run the rstatd service. If you selectruptime, each real server must run the rwhod service.

• Scheduling: The preferred scheduling algorithm from thedrop-down menu. The default is Weighted least-connection.

• Persistence: Used if you need persistent connections tothe virtual server during client transactions. Specifies thenumber of seconds of inactivity allowed to lapse before aconnection times out in this text field.

• Persistence Network Mask To limit persistence toparticular subnet, select the appropriate network maskfrom the drop-down menu.

REAL SERVERS Subsection

Click the ADD button to add a new server. To delete an existingserver, select the radio button beside it and click the DELETE button.Click the EDIT button to load the EDIT REAL SERVER panel

REAL SERVERS Subsection

Name A descriptive name for the real server.Address The real server's IP address.Weight An integer value indicating this host's capacity relative to that of otherhosts in the pool.

EDIT MONITORING SCRIPTS Subsection

EDIT MONITORING SCRIPTS SubsectionSending Program: You can use this field to specify the path to a service-checking script. This function is especially helpful for services thatrequire dynamically changing data, such as HTTPS or SSL.

Send: A string for the nanny daemon to send to each real server in thisfield. By default the send field is completed for HTTP. If you leave thisfield blank, the nanny daemon attempts to open the port and assumethe service is running if it succeeds.

Only one send sequence is allowed in this field, and it can only containprintable, ASCII characters as well as the following escape characters:\n for new line. \r for carriage return.\t for tab. \ to escape the next character which follows it.

Expect: The textual response the server should return if it is functioningproperly.

rhel cluster basics 3

Technology

cluster tab luci

cluster infrastructure

cluster member

integration of cluster

luci server

luci database

luci instance

red hat cluster suite