HP serviceguard t2808-90006 manual Dev/hpdev/mylink-sdf

Page 89

 

 

 

Disaster Scenarios and Their Handling

Table 4-1

Disaster Scenarios and Their Handling (Continued)

 

 

 

 

Disaster Scenario

What Happens When

Recovery Process

This Disaster Occurs

 

 

 

 

 

 

This is a multiple failure

The package (P1) continues

For the first failure scenario,

scenario where the failures

to run on N1 after the first

complete the following procedure

occur in a particular sequence in

failure, with md0 consisting

to initiate a recovery:

the configuration that

of only S1.

1. Restore the links in both

corresponds to figure 2 where

After the second failure, the

Ethernet and FC links do not go

directions between the data

package (P1) fails over to

over DWDM.

 

centers. As a result, S2

 

N2 and starts with S1.

 

 

(/dev/hpdev/mylink-sdf) is

The package (P1) is running on

Since S2 is also accessible,

accessible from N1 and S1 is

a node (N1). P1 uses a mirror

the extended distance

accessible from N2.

md0 consisting of S1 (local to

cluster adds S2 and starts

2. Run the following commands

node N1, say /dev/hpdev/

re-mirroring of S2.

mylink-sde) and S2 (local to

 

to remove and add S2 to md0

node N2).

 

 

on N1:

The first failure occurs with all

 

# mdadm --remove /dev/md0

FC links between the two data

 

/dev/hpdev/mylink-sdf

centers failing, causing N1 to

 

# mdadm --add /dev/md0

lose access to S2 and N2 to lose

 

 

/dev/hpdev/mylink-sdf

access to S1.

 

 

 

 

 

After recovery for the first

 

The re-mirroring process is

 

initiated. The re-mirroring process

failure has been initiated, the

 

 

starts from the beginning on N2

second failure occurs when

 

 

after the second failure. When it

re-mirroring is in progress and

 

 

completes, the extended distance

N1 goes down.

 

 

 

 

cluster detects S2 and accepts it as

 

 

 

 

 

 

part of md0 again.

 

 

 

 

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 High Availability Architecture What is a Disaster Tolerant Architecture?Node 1 fails Pkg B Client ConnectionsDisaster 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 New York Cluster Los Angeles ClusterData Cent er a Data Center B Continental ClusterBenefits of Continentalclusters Continental Cluster With Cascading Failover Comparison of Disaster Tolerant SolutionsAttributes Extended Distance Comparison of Disaster Tolerant Cluster SolutionsContinentalclusters Cluster HP-UX onlyUnderstanding 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 SourcesPower Circuit 1 node Alternative Power SourcesData Center a Node 3 Power Circuit Creating Highly Available NetworkingDisaster 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 Installing XDC Installing the Extended Distance Cluster SoftwareSupported Operating Systems Prerequisites# 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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