3.1 Administering Global Devices and the Global Namespace Overview

Administration of Sun Cluster disk device groups depends on the volume manager installed on the cluster. Solstice DiskSuite is "cluster-aware," so you add, register, and remove disk device groups by using the Solstice DiskSuite metaset(1M) command. With VERITAS Volume Manager (VxVM), you create disk groups by using VxVM commands. Then you register the disk groups as Sun Cluster disk device groups through the scsetup(1M) utility. When removing VxVM disk device groups, you use both the scsetup utility and VxVM commands.

When administering disk device groups, or volume manager disk groups, you need to be on the cluster node that is the primary node for the group.

Normally, you do not need to administer the global device namespace because the global namespace is automatically set up during installation and automatically updated during Solaris operating environment reconfiguration reboots. However, if the global namespace needs to be regenerated or updated, you can run the scgdevs(1M) command from any cluster node. This causes the global namespace to be updated on all other cluster node members, as well as on nodes that might join the cluster in the future.

3.1.1 Global Device Permissions for Solstice DiskSuite

Changes made to global device permissions are not automatically propagated to all the nodes in the cluster for Solstice DiskSuite and disk devices. If you want to change permissions on global devices, you must manually change the permissions on all the nodes in the cluster. For example, if you want to change permissions on global device /dev/global/dsk/d3s0 to 644, you must execute

# chmod 644 /dev/global/dsk/d3s0

on all nodes in the cluster.

VxVM does not support the chmod command. To change global device permissions in VxVM, consult the VxVM administrator's guide.

3.1.2 VERITAS Volume Manager Administration Considerations

For Sun Cluster to maintain the VxVM namespace, you must register any VxVM disk group or volume changes as Sun Cluster disk device group configuration changes. Registering these changes ensures that the namespace on all cluster nodes is updated. Examples of configuration changes that impact the namespace include adding, removing, or renaming a volume; and changing the volume permissions, owner, or group ID.

Never import or deport VxVM disk groups using VxVM commands once the disk group has been registered with the cluster as a Sun Cluster disk device group. The Sun Cluster software will handle all cases where disk groups need to be imported or deported.

Each VxVM disk group must have a cluster-wide unique minor number. By default, when a disk group is created, VxVM chooses a random number that is a multiple of 1000 as that disk group's base minor number. For most configurations with only a small number of disk groups, this is sufficient to guarantee uniqueness. However, it is possible that the minor number for a newly-created disk group will conflict with the minor number of a pre-existing disk group imported on a different cluster node. In this case, attempting to register the Sun Cluster disk device group will fail. To fix this problem, the new disk group should be given a new minor number that is a unique value and then registered as a Sun Cluster disk device group.

If you are setting up a mirrored volume, Dirty Region Logging (DRL) can be used to decrease volume recovery time in the event of a system crash. Use of DRL is strongly recommended, although it could decrease I/O throughput.