Sun Cluster Software Installation Guide for Solaris OS

Planning the Global Devices, Device Groups, and Cluster File Systems

This section provides the following guidelines for planning global devices and for planning cluster file systems:

Global Devices

For information about the purpose and function of global devices, see Devices in Sun Cluster Overview for Solaris OS and Global Devices in Sun Cluster Concepts Guide for Solaris OS.

Sun Cluster software does not require any specific disk layout or file system size. Consider the following points when you plan your layout for global devices.

Device Groups

For information about the purpose and function of device groups, see Devices in Sun Cluster Overview for Solaris OS and Device Groups in Sun Cluster Concepts Guide for Solaris OS.

Add this planning information to the Device Group Configurations Worksheet.

Consider the following points when you plan device groups.

Cluster File Systems

For information about the purpose and function of cluster file systems, see Cluster File Systems in Sun Cluster Overview for Solaris OS and Cluster File Systems in Sun Cluster Concepts Guide for Solaris OS.


Note –

You can alternatively configure highly available local file systems. This can provide better performance to support a data service with high I/O, or to permit use of certain file-system features that are not supported in a cluster file system.. For more information, see Enabling Highly Available Local File Systems in Sun Cluster Data Services Planning and Administration Guide for Solaris OS.


Consider the following points when you plan cluster file systems.

Choosing Mount Options for Cluster File Systems

This section describes requirements and restrictions for the following types of cluster file systems:


Note –

You can alternatively configure these and other types of file systems as highly available local file systems. For more information, see Enabling Highly Available Local File Systems in Sun Cluster Data Services Planning and Administration Guide for Solaris OS.


Follow these guidelines to determine what mount options to use when you create your cluster file systems.

UFS Cluster File Systems

Mount Option 

Usage 

Description 

global

Required 

This option makes the file system globally visible to all nodes in the cluster. 

logging

Required 

This option enables logging. 

forcedirectio

Conditional 

This option is required only for cluster file systems that will host Oracle RAC RDBMS data files, log files, and control files. 


Note –

Oracle RAC is supported for use only in SPARC based clusters.


onerror=panic

Required 

You do not have to explicitly specify the onerror=panic mount option in the /etc/vfstab file. This mount option is already the default value if no other onerror mount option is specified.


Note –

Only the onerror=panic mount option is supported by Sun Cluster software. Do not use the onerror=umount or onerror=lock mount options. These mount options are not supported on cluster file systems for the following reasons:

  • Use of the onerror=umount or onerror=lock mount option might cause the cluster file system to lock or become inaccessible. This condition might occur if the cluster file system experiences file corruption.

  • The onerror=umount or onerror=lock mount option might cause the cluster file system to become unmountable. This condition might thereby cause applications that use the cluster file system to hang or prevent the applications from being killed.

A node might require rebooting to recover from these states.


syncdir

Optional 

If you specify syncdir, you are guaranteed POSIX-compliant file system behavior for the write() system call. If a write() succeeds, then this mount option ensures that sufficient space is on the disk.

If you do not specify syncdir, the same behavior occurs that is seen with UFS file systems. When you do not specify syncdir, performance of writes that allocate disk blocks, such as when appending data to a file, can significantly improve. However, in some cases, without syncdir you would not discover an out-of-space condition (ENOSPC) until you close a file.

You see ENOSPC on close only during a very short time after a failover. With syncdir, as with POSIX behavior, the out-of-space condition would be discovered before the close.

See the mount_ufs(1M) man page for more information about UFS mount options.

VxFS Cluster File Systems

Mount Option 

Usage 

Description 

global

Required 

This option makes the file system globally visible to all nodes in the cluster. 

log

Required 

This option enables logging. 

See the VxFS mount_vxfs man page and Overview of the Administering Cluster File Systems in Sun Cluster System Administration Guide for Solaris OS for more information about VxFS mount options.

Mount Information for Cluster File Systems

Consider the following points when you plan mount points for cluster file systems.