HP serviceguard t2808-90006 manual Cluster Extension CLX Cluster

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Disaster Tolerance and Recovery in a Serviceguard Cluster

Understanding Types of Disaster Tolerant Clusters

Cluster Extension (CLX) Cluster

A Linux CLX cluster is similar to an HP-UX metropolitan cluster and is a cluster that has alternate nodes located in different parts of a city or in nearby cities. Putting nodes further apart increases the likelihood that alternate nodes will be available for failover in the event of a disaster.

The architectural requirements are the same as for an extended distance cluster, with the additional constraint of a third location for arbitrator node(s) or quorum server. And as with an extended distance cluster, the distance separating the nodes in a metropolitan cluster is limited by the data replication and network technology available.

In addition, there is no hard requirement on how far the third location has to be from the two main data centers. The third location can be as close as the room next door with its own power source or can be as far as in a site across town. The distance between all three locations dictates the level of disaster tolerance a metropolitan cluster can provide.

On Linux, the metropolitan cluster is implemented using CLX.

•CLX for XP

•CLX for EVA

For HP-UX, Metropolitan cluster architecture is implemented through the following HP products:

•Metrocluster with Continuous Access XP

•Metrocluster with Continuous Access EVA

•Metrocluster with EMC SRDF

The above HP-UX products are described in detail in Chapters 3, 4, and 5 of the Designing Disaster Tolerant HA Clusters Using Metrocluster and Continentalclusters user’s guide. The Linux products are described in detail in Getting Started with MC/ServiceGuard for Linux guide. While there are some differences between the HP-UX and the Linux versions, the concepts are similar enough that only Cluster Extension (CLX) will be described here.

On-line versions of the above document and other HA documentation are available at http://docs.hp.com -> High Availability.

On-line versions of the Cluster Extension documentation is available at

http://h71028.www7.hp.com/enterprise/cache/120851-0-0-225-12

1.html-> HP StorageWorks Cluster Extension EVA or XP.

Chapter 1

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Contents Page Legal Notices Contents Disaster Scenarios and Their Handling Managing an MD Device Contents Contents Editions and Releases Printing HistoryHP Printing Division Document Organization Intended AudiencePage Related Page Disaster Tolerance Evaluating the Need for Disaster Tolerance Evaluating the Need for Disaster Tolerance Pkg B Client Connections What is a Disaster Tolerant Architecture?High Availability Architecture Node 1 failsDisaster Tolerant Architecture Extended Distance Clusters Understanding Types of Disaster Tolerant ClustersFrom both storage devices Extended Distance Cluster Two Data Center Setup Benefits of Extended Distance Cluster Cluster Extension CLX Cluster CLX for Linux Serviceguard Cluster Shows a CLX for a Linux Serviceguard cluster architectureBenefits of CLX Differences Between Extended Distance Cluster and CLX Continental Cluster Continental Cluster Los Angeles ClusterNew York Cluster Data Cent er a Data Center BBenefits of Continentalclusters Continental Cluster With Cascading Failover Comparison of Disaster Tolerant SolutionsCluster HP-UX only Comparison of Disaster Tolerant Cluster SolutionsAttributes Extended Distance ContinentalclustersUnderstanding Types of Disaster Tolerant Clusters Understanding Types of Disaster Tolerant Clusters Understanding Types of Disaster Tolerant Clusters WAN EVA Protecting Nodes through Geographic Dispersion Disaster Tolerant Architecture GuidelinesOff-line Data Replication Protecting Data through ReplicationPhysical Data Replication On-line Data ReplicationDisadvantages of physical replication in hardware are Advantages of physical replication in hardware areAdvantages of physical replication in software are Logical Data Replication Disadvantages of physical replication in software areDisadvantages of logical replication are Ideal Data Replication Using Alternative Power SourcesCreating Highly Available Networking Alternative Power SourcesPower Circuit 1 node Data Center a Node 3 Power CircuitDisaster Tolerant Wide Area Networking Disaster Tolerant Local Area NetworkingDisaster Tolerant Cluster Limitations Managing a Disaster Tolerant Environment Manage it in-house, or hire a service?How is the cluster maintained? Additional Disaster Tolerant Solutions Information Building an Extended Distance Dwdm Types of Data Link for Storage NetworkingTwo Data Center and Quorum Service Location Architectures Two Data Center and Quorum Service Location Architectures Server Two Data Centers and Third Location with Dwdm and QuorumTwo Data Center and Quorum Service Location Architectures Rules for Separate Network and Data Links Guidelines on Dwdm Links for Network and Data Guidelines on Dwdm Links for Network and Data Guidelines on Dwdm Links for Network and Data Chapter Configuring your Environment Understanding Software RAID Prerequisites Installing the Extended Distance Cluster SoftwareInstalling XDC Supported Operating Systems# rpm -Uvh xdc-A.01.00-0.rhel4.noarch.rpm Verifying the XDC InstallationInstalling the Extended Distance Cluster Software Configuring the Environment Configuring the Environment Configuring the Environment Setting the Value of the Link Down Timeout Parameter Configuring Multiple Paths to StorageCluster Reformation Time and Timeout Values Http//docs.hp.com Using Persistent Device NamesTo Create and Assemble an MD Device Creating a Multiple Disk Device# mdadm -A -R /dev/md0 /dev/hpdev/sde1 /dev/hpdev/sdf1 Chapter Linux #RAIDTAB= # MD RAID Commands To Edit the Datarep Variable Creating and Editing the Package Control ScriptsTo Create a Package Control Script Editing the raid.conf File To Edit the Xdcconfig File parameterTo Configure the RAID Monitoring Service Cases to Consider when Setting Rpotarget RPO Target Definitions Chapter Multipledevices and Componentdevices Raidmonitorinterval Configuring your Environment for Software RAID Disaster Scenario What happens when this disaster occursRecovery Process Disaster Scenarios and Their Handling Disaster Scenarios and Their Handling# mdadm --remove /dev/md0 # mdadm -add /dev/md0 Dev/hpdev/mylink-sdf P1 uses a mirror md0 Run the following command to S2 is non-current by less # cmrunpkg packagename Execute the commands that With md0 consisting of only N1, for example Becomes accessible from N2 Center Disaster Scenarios and Their Handling Managing an MD Device Cat /proc/mdstat Viewing the Status of the MD DeviceExample A-1 Stopping the MD Device /dev/md0 Stopping the MD DeviceExample A-2 Starting the MD Device /dev/md0 Starting the MD Device# udevinfo -q symlink -n sdc1 Removing and Adding an MD Mirror Component Disk# mdadm --remove /dev/md0 /dev/hpdev/sde Adding a Mirror Component DeviceIndex 104