HP serviceguard t2808-90006 manual Cases to Consider when Setting Rpotarget

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Configuring your Environment for Software RAID

Configuring the Package Control Script and RAID Configuration File

 

more time elapses than what is specified for RPO_TARGET, the

 

package is prevented from starting on the remote node (assuming

 

that the node still has access only to its own half of the mirror).

 

By default, RPO_TARGET is set to 0. Leave it at 0 to ensure the

 

package does not start on an adoptive node with a mirror half that is

 

not current. This ensures the highest degree of data currency.

 

If RPO_TARGET is not set to 0, the value of RAID_MONITOR_INTERVAL

 

should be less than the value of RPO_TARGET.

 

(RAID_MONITOR_INTERVAL should also be less than the value of the

 

Link_Down_Timeout parameter so that disk access failure can be

 

recognized early enough in certain failure scenarios.)

 

 

IMPORTANT

A very low value of RAID_MONITOR_INTERVAL (less than 5 seconds)

 

has some impact on system performance because of the high

 

frequency of polling.

 

You can also set RPO_TARGET to the special value -1or to any positive

 

 

integer. Setting RPO_TARGET to -1causes the RAID system to ignore

 

any time-window checks on the disk set. This allows the package to

 

start with a mirror half that is not current.

 

Setting the RPO_TARGET to any positive integer, means that the

 

package will start with a mirror half that is not current by any

 

number of seconds less than that value. For example, an RPO_TARGET

 

of 45 means that the package will start only if the mirror is up to

 

date, or out of date by less than 45 seconds.

 

Because some timers are affected by polling, the value of this

 

parameter can vary by approximately 2 seconds.

 

This also requires that the minimum value of this parameter is 2

 

seconds if a small value is necessary. Change the value of

 

RPO_TARGET, if necessary, after considering the cases discussed

 

below.

 

Cases to Consider when Setting RPO_TARGET

 

RPO_TARGET allows for certain failure conditions when data is not

 

synchronized between the two sites.

Chapter 3

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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 Create a Package Control Script Creating and Editing the Package Control ScriptsTo Edit the Datarep Variable To Configure the RAID Monitoring Service To Edit the Xdcconfig File parameterEditing the raid.conf File Cases to Consider when Setting Rpotarget RPO Target Definitions Chapter Multipledevices and Componentdevices Raidmonitorinterval Configuring your Environment for Software RAID Recovery Process What happens when this disaster occursDisaster 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