HP UX Serviceguard Storage Management Software manual Asymmetric Mounts

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Cluster File System Administration

Cluster File System Overview

Asymmetric Mounts

Asymmetric mounts allow shared file systems to be mounted with different read/write capabilities. One node in the cluster can mount read-write, while other nodes mount read-only.

You can specify the cluster read-write (crw) option when you first mount the file system. The first column in the following table shows the mode in which the primary is mounted. The “X” marks indicate the modes available to secondary nodes in the cluster.

See the mount_vxfs(1M) manual page for more information.

Table 3-1

Primary and Secondary Mount Options

 

 

 

 

 

 

 

Secondary:

Secondary:

Secondary:

 

 

ro

rw

ro, crw

 

 

 

 

 

 

Primary:

X

 

 

 

ro

 

 

 

 

 

 

 

 

 

Primary:

 

X

X

 

rw

 

 

 

 

 

 

 

 

 

Primary:

 

X

X

 

ro, crw

 

 

 

 

 

 

 

 

Mounting the primary node with only the -o cluster,ro option prevents the secondary nodes from mounting in the read-write mode. Note that mounting the primary node with the rw option implies read-write capability throughout the cluster.

Chapter 3

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Contents Second Edition Legal Notices Contents Troubleshooting Cluster Volume Manager AdministrationPrinting History Printing HistoryPage Technical Overview Cluster File System Design Overview of Cluster File System ArchitectureCluster File System Failover Group Lock ManagerSupported Features CFS Supported FeaturesVxFS Functionality on Cluster File Systems CFS Unsupported Features Unsupported FeaturesCFS Unsupported Features Benefits and Applications Advantages To Using CFSWhen To Use CFS Benefits and Applications Chapter Cluster File System Architecture Role of Component Products Veritas Cluster Volume Manager FunctionalityCluster Communication Membership PortsAbout CFS Cluster File System and The Group Lock ManagerAsymmetric Mounts Primary and Secondary Mount Options Parallel I/OCluster File System Backup Strategies Synchronizing Time on Cluster File Systems Error Handling PolicyDistributing Load on a Cluster File System TuneablesExample of a Four-Node Cluster About Veritas Cluster Volume Manager FunctionalityPrivate and Shared Disk Groups Activation Modes for Shared Disk Groups Activation Modes for Shared Disk GroupsAllowed and conflicting activation modes Connectivity Policy of Shared Disk GroupsLimitations of Shared Disk Groups About Veritas Cluster Volume Manager Functionality Chapter Cluster File System Administration Cluster File System Administration Cluster Messaging GAB Cluster Communication LLT Volume Manager Cluster Functionality Overview Cluster and Shared Mounts Cluster File System OverviewAsymmetric Mounts Cluster File System Commands Cluster File System AdministrationGrowing a Cluster File System Time Synchronization for Cluster File SystemsFstab file Distributing the Load on a ClusterCluster File System Administration Snapshots for Cluster File Systems Cluster Snapshot CharacteristicsPerformance Considerations Creating a Snapshot on a Cluster File System# cfsumount /mnt1snap Cluster Volume Manager Overview of Cluster Volume Management Example of a 4-Node Cluster Disk group activation mode restrictions Either of the write modes on other nodes will fail # cfsdgadm display Behavior of Master Node for Different Failure Policies Disk Group Failure PolicyRecovery in a CVM Environment Troubleshooting Inaccessible System Installation IssuesIncorrect Permissions for Root on Remote System Resource Temporarily UnavailableInstallation Issues Cluster File System Problems Unmount FailuresMount Failures Command Failures Performance IssuesHigh Availability Issues Cluster File System Problems Appendix a