HP serviceguard t2808-90006 manual Center

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Disaster Scenarios and Their Handling

Table 4-1

Disaster Scenarios and Their Handling (Continued)

 

 

 

 

Disaster Scenario

What Happens When

Recovery Process

This Disaster Occurs

 

 

 

 

 

 

In this case, initially the

With this failure, the

Complete the following steps to

package (P1) is running on node

heartbeat exchange is lost

initiate a recovery:

N1. P1 uses a mirror md0

between N1 and N2. This

1. You need to only restore the

consisting of S1 (local to node

results in both nodes trying

N1, for example

 

to get to the Quorum server.

Ethernet links between the

/dev/hpdev/mylink-sde) and

If N1 accesses the Quorum

data centers so that N1 and

S2 (local to node N2). The first

N2 can exchange heartbeats

server first, the package

failure occurs with all Ethernet

2. After restoring the links, you

continues to run on N1 with

links between the two data

S1 and S2 while N2 is

must add the node that was

centers failing.

 

 

rebooted. If N2 accesses the

rebooted as part of the cluster.

 

 

 

 

Quorum server, the package

Run the cmrunnode command

 

 

fails over to N2 and starts

to add the node to the cluster.

 

 

running with both S1 and

NOTE: If this failure is a

 

 

S2 and N1 is rebooted.

 

 

precursor to a site failure, and if

 

 

 

 

 

 

the Quorum Service arbitration

 

 

 

selects the site that is likely to

 

 

 

have a failure, it is possible that

 

 

 

the entire cluster will go down.

 

 

 

In this case, initially the

With this failure, the

Complete the following procedure

package (P1) is running on node

heartbeat exchange

to initiate a recovery:

N1. P1 uses a mirror md0

between N1 and N2 is lost.

1. Restore the Ethernet links

consisting of S1 (local to node

N2 accesses the Quorum

N1, say

 

from N1 to the switch in data

 

server, as it is the only node

/dev/hpdev/mylink-sde) and

center 1.

which has access to the

S2 (local to node N2). The first

2. After restoring the links, you

Quorum server. The

failure occurs when the

package fails over to N2 and

must add the node that was

Ethernet links from N1 to the

starts running with both S1

rebooted as part of the cluster.

Ethernet switch in datacenter1

and S2 while N1 gets

Run the cmrunnode command

fails.

 

 

rebooted.

to add the node to the cluster.

 

 

 

 

 

 

Chapter 4

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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
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