Red Hat CLUSTER SUITE FOR ENTERPRISE LINUX 5.2 Guida di Installazione

Red Hat Cluster Suite OverviewRed Hat Cluster Suite forRed Hat Enterprise Linux5.2Cluster_Suite_OverviewISBN: N/APublication date: May 2008

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Red Hat Cluster Suite OverviewClustered systems provide reliability, scalability, and availability to critical production services.Using Red Hat Clust

High-availability clusters provide continuous availability of services by eliminating single pointsof failure and by failing over services from one cl

Infrastructure components, the High-availability and Service Management components, andstorage.• Linux Virtual Server (LVS) — Routing software that pr

Figure 1.1. Red Hat Cluster Suite IntroductionNoteFigure 1.1, “Red Hat Cluster Suite Introduction” includes GFS, CLVM, andGNBD, which are components t

the node votes plus 1. For quorum via quorum disk, quorum consists of user-specifiedconditions.NoteBy default, each node has one quorum vote. Optional

distributed across all nodes in the cluster (refer to Figure 1.2, “CMAN/DLM Overview”). GFS andCLVM use locks from the lock manager. GFS uses locks fr

Figure 1.3. Power Fencing ExampleFencing7

Figure 1.4. Fibre Channel Switch Fencing ExampleSpecifying a fencing method consists of editing a cluster configuration file to assign afencing-method

Figure 1.5. Fencing a Node with Dual Power SuppliesFencing9

Red Hat Cluster Suite Overview provides an overview of Red Hat Cluster Suite for Red HatEnterprise Linux 5.2Red Hat Cluster Suite Overview

Figure 1.6. Fencing a Node with Dual Fibre Channel ConnectionsYou can configure a node with one fencing method or multiple fencing methods. When youco

The Cluster Configuration System (CCS) manages the cluster configuration and providesconfiguration information to other cluster components in a Red Ha

Figure 1.8. Accessing Configuration InformationThe cluster configuration file (/etc/cluster/cluster.conf) is an XML file that describes thefollowing c

High-availability service management provides the ability to create and manage high-availabilitycluster services in a Red Hat cluster. The key compone

Figure 1.9. Failover DomainsFigure 1.10, “Web Server Cluster Service Example” shows an example of a high-availabilitycluster service that is a web ser

Figure 1.10. Web Server Cluster Service ExampleClients access the cluster service through the IP address 10.10.10.201, enabling interactionwith the we

uses a lock manager to coordinate I/O. When one node changes data on a GFS file system,that change is immediately visible to the other cluster nodes u

• Section 5.1, “Superior Performance and Scalability”• Section 5.2, “Performance, Scalability, Moderate Price”• Section 5.3, “Economy and Performance”

Figure 1.12, “GFS and GNBD with a SAN”. SAN block storage is presented to network clientsas block storage devices by GNBD servers. From the perspectiv

Figure 1.13. GFS and GNBD with Directly Connected Storage6. Cluster Logical Volume ManagerThe Cluster Logical Volume Manager (CLVM) provides a cluster

Red Hat Cluster Suite Overview: Red Hat Cluster Suite forRed Hat Enterprise LinuxCopyright © 2008 Red Hat, Inc.Copyright © 2008 Red Hat, Inc. This mat

Using CLVM requires minor changes to /etc/lvm/lvm.conf for cluster-widelocking.Figure 1.14. CLVM OverviewYou can configure CLVM using the same command

Figure 1.15. LVM Graphical User InterfaceCluster Logical Volume Manager21

Figure 1.16. Conga LVM Graphical User InterfaceChapter 1. Red Hat Cluster Suite Overview22

Figure 1.17. Creating Logical Volumes7. Global Network Block DeviceGlobal Network Block Device (GNBD) provides block-device access to Red Hat GFS over

Figure 1.18. GNBD Overview8. Linux Virtual ServerLinux Virtual Server (LVS) is a set of integrated software components for balancing the IP loadacross

Figure 1.19. Components of a Running LVS ClusterThe pulse daemon runs on both the active and passive LVS routers. On the backup LVSrouter, pulse sends

To an outside user accessing a hosted service (such as a website or database application),LVS appears as one server. However, the user is actually acc

1A virtual server is a service configured to listen on a specific virtual IP.Figure 1.20. Two-Tier LVS TopologyService requests arriving at an LVS rou

• Round-Robin Scheduling — Distributes each request sequentially around a pool of realservers. Using this algorithm, all the real servers are treated

The backup LVS router performs the role of a standby system. Periodically, the LVS routersexchange heartbeat messages through the primary external pub

Red Hat Cluster Suite Overview

Figure 1.21. Three-Tier LVS TopologyThis topology is suited well for busy FTP servers, where accessible data is stored on a central,highly available s

a Red Hat cluster, you can configure one high-availability cluster to serve both of these rolessimultaneously.8.3. Routing MethodsYou can use Network

interface are taken over by the backup LVS router simultaneously. All the real servers on theprivate network use the floating IP for the NAT router as

Figure 1.23. LVS Implemented with Direct RoutingIn a typical direct-routing LVS configuration, an LVS router receives incoming server requeststhrough

In typical situations, a client on the Internet sends a request to an IP address. Network routerstypically send requests to their destination by relat

8.4.2. Firewall MarksFirewall marks are an easy and efficient way to a group ports used for a protocol or group ofrelated protocols. For example, if L

luci is accessible through a Web browser and provides three major functions that areaccessible through the following tabs:• homebase — Provides tools

Figure 1.24. luci homebase TabFigure 1.25. luci cluster TabConga37

Figure 1.26. luci storage Tab9.2. Cluster Administration GUIThis section provides an overview of the system-config-cluster cluster administrationgraph

9.2.1. Cluster Configuration ToolYou can access the Cluster Configuration Tool (Figure 1.27, “Cluster Configuration Tool”)through the Cluster Configur

Introduction ... vii1. Document Conventions

• Cluster Nodes — Displays cluster nodes. Nodes are represented by name as subordinateelements under Cluster Nodes. Using configuration buttons at the

Cluster Management tab in Cluster Administration GUI.Figure 1.28. Cluster Status ToolThe nodes and services displayed in the Cluster Status Tool are d

Administration GUI and init scripts supplied by Red Hat. Table 1.1, “Command Line Tools”summarizes the command line tools.Command LineToolUsed With Pu

Web browser. You can access it locally with this URL: http://localhost:3636. You canaccess it remotely with either the hostname or the real IP address

Figure 1.30. The CONTROL/MONITORING PanelAuto updateEnables the status display to be updated automatically at a user-configurable interval set inthe U

10.2. GLOBAL SETTINGSThe GLOBAL SETTINGS panel is where the LVS administrator defines the networking detailsfor the primary LVS router's public a

The next three fields are specifically for the NAT router's virtual network interface connected theprivate network with the real servers.NAT Rout

Figure 1.32. The REDUNDANCY PanelRedundant server public IPThe public real IP address for the backup LVS router.Redundant server private IPThe backup

Figure 1.33. The VIRTUAL SERVERS PanelEach server displayed in the VIRTUAL SERVERS panel can be configured on subsequentscreens or subsections.To add

any of the subsections related to this virtual server, complete this page and click on theACCEPT button.Figure 1.34. The VIRTUAL SERVERS SubsectionNam

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Virtual IP Network MaskThe netmask for this virtual server, in the drop-down menu.Firewall MarkFor entering a firewall mark integer value when bundlin

drop-down menu.10.4.2. REAL SERVER SubsectionClicking on the REAL SERVER subsection link at the top of the panel displays the EDIT REALSERVER subsecti

Figure 1.36. The REAL SERVER Configuration PanelThis panel consists of three entry fields:NameA descriptive name for the real server.TipThis name is n

WeightAn integer value indicating this host's capacity relative to that of other hosts in the pool. Thevalue can be arbitrary, but treat it as a

dynamically changing data, such as HTTPS or SSL.To use this function, you must write a script that returns a textual response, set it to beexecutable,

Red Hat Cluster Suite ComponentSummaryThis chapter provides a summary of Red Hat Cluster Suite components and consists of thefollowing sections:• Sect

Function Components Descriptioncreated with GFS 6.0 (and earlier) tothe XML format configuration formatused with this release of Red HatCluster Suite.

Function Components Descriptionmembership and services running.clurgmgrd Daemon used to handle user servicerequests including service start,service di

Function Components Descriptionenvironments.fence_ack_manual User interface for fence_manualagent.fence_node A program which performs I/O fencingon a

Function Components Descriptiongnbd_serv A server daemon that allows a nodeto export local storage over thenetwork.LVS pulse This is the controlling p

IntroductionThis document provides a high-level overview of Red Hat Cluster Suite for Red Hat EnterpriseLinux 5 and is is organized as follows:• Chapt

Function Components Descriptionnanny The nanny monitoring daemon runson the active LVS router. Through thisdaemon, the active LVS routerdetermines the

• ccs (7) - Cluster Configuration System• cman_tool (8) - Cluster Management Tool• cluster.conf [cluster] (5) - The configuration file for cluster pro

• fence_xvm (8) - I/O Fencing agent for Xen virtual machines• fence_xvmd (8) - I/O Fencing agent host for Xen virtual machines• fenced (8) - the I/O F

• pulse (8) - heartbeating daemon for monitoring the health of cluster nodes• lvs.cf [lvs] (5) - configuration file for lvs• lvscan (8) - scan (all di

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IndexCclusterdisplaying status, 41cluster administrationdisplaying cluster and service status, 41cluster component compatible hardware, 63cluster comp

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PDF, and RPM versions on the Red Hat Enterprise Linux Documentation CD and online athttp://www.redhat.com/docs/.1. Document ConventionsCertain words i

TipA tip is typically an alternative way of performing a task.ImportantImportant information is necessary, but possibly unexpected, such as aconfigura