PRIMECLUSTER Global Disk Services Configuration and Administration Guide 4.1 (Solaris(TM) Operating System)

2.7.2.1 Shadow Class

A shadow class is the shadow object corresponding to a disk class that is an SDX object.

When disk classes and shadow classes do not have to be classified particularly, they may be called "classes" collectively.

Physical disks conforming to one of the following conditions can be registered with shadow classes.

• Disks registered with a class (local class or shared class) of GDS or SynfinityDisk in another domain and managed as SDX disks
  If this applies, with one shadow class, a physical disk registered with the class that has the same name in another domain can be registered. When multiple physical disks are registered with one class in another domain, part or all of those disks can be registered with a shadow class. It is also possible to register part of those disks to a shadow class and the other to another shadow class.

• Disks to which the private slice was copied from an SDX disk registered with a class (local class or shared class) of GDS or SynfinityDisk in another domain or the same domain with the disk unit's copy function
  If this applies, with one shadow class, a copy destination physical disk of the SDX disk registered with the class that has the same name can be registered. When multiple physical disks are registered with one class, part or all of such copy destination physical disks can be registered with a shadow class. It is also possible to register part of such copy destination physical disks to a shadow class and the other to another shadow class.

In addition, the sizes of the private slices of physical disks to be registered with the same shadow class must be the same.

 

Attributes

A shadow class has the following attributes.

Name

This attribute identifies the shadow class in a system.

Type

This attribute indicates the type of shadow class. The following value is set.

Local

The object managed in a shadow class is available only on the current node.

Scope

This attribute indicates a group of nodes on which objects in the shadow class are available. The current node name is set.

 

Operation

The operations other than status display are not available from Management View. Use the command for each operation.

Create

A new shadow class will be automatically created by specifying a new class name when registering a disk with the sdxshadowdisk -M command.

Delete

The shadow class will be automatically deleted by deleting the last registered shadow disk from a shadow class with the sdxshadowdisk -R command.

Status Display

The shadow class status can be displayed with the sdxinfo command. A shadow class is indicated by 1 (one) in the SHADOW field for class information displayed with the sdxinfo -e long command.
For details on GDS Management View, see "Viewing Configurations and Monitoring Statuses."

 

Status

Unlike a disk class, there is no possibility that a shadow class is closed down.

 

Reference

There are the following points of concern for shadow classes.

Rules

Object Name

Number of Classes

Important Points

Physical Disk Driver

Operation in Cluster System

 

The disks that are registered with a class in a certain domain (domain alpha in the figure below) and accordingly are managed as SDX disks can be registered with a shadow class in another domain (domain beta in the figure below) connected to the same SAN.

[Figure: Example of Common Configuration with a Shadow Class]

The disk (c1t1d2 in the figure below) to which the private slice has been copied from an SDX disk (c1t1d1 in the figure below) with the disk unit's copy function can be registered with a shadow class on one of the following nodes.

• Node that is included in the scope of the class to which the SDX disk belongs (node1 or node 2 in the figure below)

• Node that belongs to the domain (domain alpha in the figure below) with which the SDX disk is registered, but that is not included in the scope of its class (node 3 in the figure below)

• Node that does not belong to the domain where the SDX disk is registered (domain alpha in the figure below), but that is connected to the same SAN (node 4 in the figure above)

[Figure: Example of Configuration Using Disk Unit's Copy Function and a Shadow Class]

Physical Device Name
The same physical device name (such as c1t1d1) is not necessarily assigned to the identical physical device in domain alpha and domain beta.