Managing Shared Disks

Changing the states of Virtual Shared Disks

Changes to your configuration or problems in your system, application, or network involve activities that move your virtual shared disks from one state (such as stopped, suspended, or active) to another. If you are not using the IBM Recoverable Virtual Shared Disk component, you might have to perform an activity that results in such a change. (The IBM Recoverable Virtual Shared Disk subsystem changes the states of your virtual shared disks for you, automatically.)

Several activities result in a virtual shared disk state change.

Starting a Virtual Shared Disk

Starting puts a stopped virtual shared disk in the active (and available) state. (This is equivalent to preparing and resuming a virtual shared disk.) Note that for a virtual shared disk to be usable, it must be in the active state on both the server and client nodes.

Note:

If you are starting or resuming a virtual shared disk manually, you must ensure that the volume group is varied online to one of the servers. It is also important that you explicitly specify the server to be used in the command syntax. If you use only startvsd vsdname, the default will be the primary server, which may not be available.

Preparing a Virtual Shared Disk

Preparing puts a stopped virtual shared disk in the suspended state. In the suspended state, open and close requests are honored. Read and write requests are held until the virtual shared disk is brought to the active state.

Resuming a Virtual Shared Disk

Resuming a virtual shared disk puts a suspended virtual shared disk in the active state. The virtual shared disk remains available and read and write requests that were held are resumed.

Note:

If you are starting or resuming a virtual shared disk manually, you must ensure that the volume group is varied online to one of the servers. It is also important that you explicitly specify the server to be used in the command syntax. If you use only startvsd vsdname, the default will be the primary server, which may not be available.

Suspending a Virtual Shared Disk

Suspending puts an active virtual shared disk in the suspended state. The virtual shared disk remains available. Read and write requests that were active are suspended and held. All read and write requests subsequent to those that were active are also held.

Stopping a Virtual Shared Disk

Stopping puts a suspended virtual shared disk in the stopped state. The virtual shared disk becomes unavailable. All applications that have outstanding requests to a stopped virtual shared disk terminate in error.

Unconfiguring a stopped virtual shared disk makes it inaccessible. It does not, however, undefine or change the definition information for the virtual shared disk in the SDR.

Changing a Virtual Shared Disk state using actions

Note:

If you use IBM Recoverable Virtual Shared Disk, do not directly change the state of the virtual shared disks. IBM Recoverable Virtual Shared Disk handles state changes for you. Making such changes could cause the recovery process that IBM Recoverable Virtual Shared Disk manages to fail.

Note:

If you use IBM Recoverable Virtual Shared Disk, in general you should not issue any commands that change the state of the virtual shared disks (for example cfgvsd, cfghsdvsd, startvsd, preparevsd, resumevsd, suspendvsd, stopvsd, ucfgvsd, or ucfghsdvsd). IBM Recoverable Virtual Shared Disk handles state changes for you. Making such changes could cause the virtual shared disks to end up in a state that will not be managed correctly by IBM Recoverable Virtual Shared Disk. There are some cases where it is necessary to issue commands that change the state of the virtual shared disks. Two such cases are:

• Adding a virtual shared disk
• Removing a virtual shared disk

To change the state of a virtual shared disk using the IBM Virtual Shared Disk Perspective graphical user interface, you can do the following:

1. Click on the virtual shared disk node icon to select it
2. Click on Actions>Change VSDs State...

A dialog window is opened. It contains two selection boxes. The one on the right has a list from which you can choose virtual shared disks. The one on the left collects your choices. You can set them to active, suspended, or stopped.

Changing a Virtual Shared Disk state using commands

Note:

If you use IBM Recoverable Virtual Shared Disk, do not issue any commands that change the state of the virtual shared disks (cfgvsd, cfghsdvsdstartvsd, preparevsd, resumevsd, suspendvsd, stopvsd, ucfgvsd, or ucfghsdvsd). IBM Recoverable Virtual Shared Disk handles state changes for you. Issuing any of these commands could cause the recovery process that IBM Recoverable Virtual Shared Disk manages to fail.

Note:

If you use IBM Recoverable Virtual Shared Disk, in general you should not issue any commands that change the state of the virtual shared disks (for example cfgvsd, cfghsdvsd, startvsd, preparevsd, resumevsd, suspendvsd, stopvsd, ucfgvsd, or ucfghsdvsd). IBM Recoverable Virtual Shared Disk handles state changes for you. Making such changes could cause the virtual shared disks to end up in a state that will not be managed correctly by IBM Recoverable Virtual Shared Disk. There are some cases where it is necessary to issue commands that change the state of the virtual shared disks. Two such cases are:

• Adding a virtual shared disk
• Removing a virtual shared disk

Figure 17 shows the commands that move virtual shared disks from one state to another.

Figure 17. Virtual Shared Disk States and Associated Commands

View figure.