HP serviceguard t2808-90006 manual Configuring the Environment

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Configuring your Environment for Software RAID

Configuring the Environment

Configuring the Environment

After setting up the hardware as described in the Extended Distance Cluster Architecture section and installing the Extended Distance Cluster software, complete the following steps to enable Software RAID for each package. Subsequent sections describe each of these processes in detail.

1.Configure multipath for storage

In the Extended Distance Cluster setup described in figures 1 and 2, a node has multiple paths to storage. With this setup each LUN exposed from a storage array shows up as two devices on every node. There are two device entries in the /dev directory for the same LUN where each device entry will pertain to a single path to that LUN. When a QLogic driver is installed and configured for multipath, all device names leading to the same physical device will be merged and only one device entry will appear in their place. This happens for devices from both the storage systems. Creating these multiple links to the storage device ensures that each node is not dependent only on one link to write data to that storage device. For more information on configuring multipath, see “Configuring Multiple Paths to Storage” on page 69.

2.Configure persistent device names for storage devices

Once the multipath has been configured, you need to create persistent device names using udev. In cases of disk or link failure and subsequent reboot, it is possible that device names are renamed or reoriented. Since the MD mirror device starts with the names of the component devices, a change in the device name prevents the MD mirror from starting. To avoid this problem, HP requires that you make the device names persistent. For more information on configuring persistent device names, see “Using Persistent Device Names” on page 71.

3.Create the MD mirror device

To enable Software RAID in your environment, you need to first create the mirror setup. This implies that you specify two disks to create a Multiple Device (MD). When configuring disks in RAID 1 level, use a disk or LUN from each datacenter as one mirror half. Be sure to create disk sets of the same size as they need to store data

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Chapter 3

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Contents Page Legal Notices Contents Disaster Scenarios and Their Handling Managing an MD Device Contents Contents Printing History Editions and ReleasesHP Printing Division Intended Audience Document OrganizationPage Related Page Disaster Tolerance Evaluating the Need for Disaster Tolerance Evaluating the Need for Disaster Tolerance Node 1 fails What is a Disaster Tolerant Architecture?High Availability Architecture Pkg B Client ConnectionsDisaster Tolerant Architecture Understanding Types of Disaster Tolerant Clusters Extended Distance ClustersFrom both storage devices Extended Distance Cluster Two Data Center Setup Benefits of Extended Distance Cluster Cluster Extension CLX Cluster Shows a CLX for a Linux Serviceguard cluster architecture CLX for Linux Serviceguard ClusterBenefits of CLX Differences Between Extended Distance Cluster and CLX Continental Cluster Data Cent er a Data Center B Los Angeles ClusterNew York Cluster Continental ClusterBenefits of Continentalclusters Comparison of Disaster Tolerant Solutions Continental Cluster With Cascading FailoverContinentalclusters Comparison of Disaster Tolerant Cluster SolutionsAttributes Extended Distance Cluster HP-UX onlyUnderstanding Types of Disaster Tolerant Clusters Understanding Types of Disaster Tolerant Clusters Understanding Types of Disaster Tolerant Clusters WAN EVA Disaster Tolerant Architecture Guidelines Protecting Nodes through Geographic DispersionProtecting Data through Replication Off-line Data ReplicationOn-line Data Replication Physical Data ReplicationAdvantages of physical replication in hardware are Disadvantages of physical replication in hardware areAdvantages of physical replication in software are Disadvantages of physical replication in software are Logical Data ReplicationDisadvantages of logical replication are Using Alternative Power Sources Ideal Data ReplicationData Center a Node 3 Power Circuit Alternative Power SourcesPower Circuit 1 node Creating Highly Available NetworkingDisaster Tolerant Local Area Networking Disaster Tolerant Wide Area NetworkingDisaster Tolerant Cluster Limitations Manage it in-house, or hire a service? Managing a Disaster Tolerant EnvironmentHow is the cluster maintained? Additional Disaster Tolerant Solutions Information Building an Extended Distance Types of Data Link for Storage Networking DwdmTwo Data Center and Quorum Service Location Architectures Two Data Center and Quorum Service Location Architectures Two Data Centers and Third Location with Dwdm and Quorum ServerTwo 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 Supported Operating Systems Installing the Extended Distance Cluster SoftwareInstalling XDC PrerequisitesVerifying the XDC Installation # rpm -Uvh xdc-A.01.00-0.rhel4.noarch.rpmInstalling the Extended Distance Cluster Software Configuring the Environment Configuring the Environment Configuring the Environment Configuring Multiple Paths to Storage Setting the Value of the Link Down Timeout ParameterCluster Reformation Time and Timeout Values Using Persistent Device Names Http//docs.hp.comCreating a Multiple Disk Device To Create and Assemble an MD 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 Viewing the Status of the MD Device Cat /proc/mdstatStopping the MD Device Example A-1 Stopping the MD Device /dev/md0Starting the MD Device Example A-2 Starting the MD Device /dev/md0Removing and Adding an MD Mirror Component Disk # udevinfo -q symlink -n sdc1Adding a Mirror Component Device # mdadm --remove /dev/md0 /dev/hpdev/sdeIndex 104