HP serviceguard t2808-90006 manual Continental Cluster

Page 27

Disaster Tolerance and Recovery in a Serviceguard Cluster

Understanding Types of Disaster Tolerant Clusters

"objective" can be set for the recovery point such that if data is updated for a period less than the objective, automated failover can occur and a package will start. If the time is longer than the objective, then the package will not start. In a Linux environment, this is a user configurable parameter: RPO_TARGET.

•Extended Distance Cluster disk reads may outperform CLX in normal operations. On the other hand, CLX data resynchronization and recovery performance are better than Extended Distance Cluster.

Continental Cluster

A continental cluster provides an alternative disaster tolerant solution in which distinct clusters can be separated by large distances, with wide area networking used between them. Continental cluster architecture is implemented using the Continentalclusters product, described fully in Chapter 2 of the Designing Disaster Tolerant HA Clusters Using Metrocluster and Continentalclusters user’s guide. This product is available only on HP-UX and not on Linux. The design is implemented with two distinct Serviceguard clusters that can be located in different geographic areas with the same or different subnet configuration. In this architecture, each cluster maintains its own quorum, so an arbitrator data center is not used for a continental cluster. A continental cluster can use any WAN connection through a TCP/IP protocol; however, due to data replication needs, high speed connections such as T1 or T3/E3 leased lines or switched lines may be required. See Figure 1-6.

NOTE	A continental cluster can also be built using multiple clusters that
	communicate over shorter distances using a conventional LAN.

Chapter 1

27

Image 27

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 Creating and Editing the Package Control Scripts To Create a Package Control ScriptTo Edit the Datarep Variable To Edit the Xdcconfig File parameter To Configure the RAID Monitoring ServiceEditing the raid.conf File Cases to Consider when Setting Rpotarget RPO Target Definitions Chapter Multipledevices and Componentdevices Raidmonitorinterval Configuring your Environment for Software RAID What happens when this disaster occurs Recovery ProcessDisaster Scenario 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