Using Interrupt Priority Level C (IPC)

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HP OpenVMS System Manager's Manual, Volume 1:...

Managing Storage Media

Using Mount Verification for Recovery

Using the Bad Block Locator Utility to Detect Media Errors

Using Interrupt Priority Level C (IPC)

IPC is a special program that issues a software interrupt to gain the attention of the console terminal. You can use IPC commands to adjust quorum in an OpenVMS cluster, to cancel mount verification, or to enter the debugger. (The debugger in this case refers to the system-level debugger, XDELTA.)

IPC commands are intended to be used only for debugging and laboratory implementation. Use of the commands might cause unexpected results.

The IPC program converts lowercase letters to uppercase, issues the terminal bell character whenever it receives illegal characters (such as most control characters), compresses multiple spaces, and ignores leading spaces.

How to Invoke IPC

On both OpenVMS VAX and Alpha systems, enter the following command from the console terminal:
```
$ Ctrl/P
```
This command does not echo. Responses to this command will be implementation-specific, which are indicated in the examples by ellipses
```
.
.
.
```

Enter subsequent commands specific to the hardware you are using:
- On VAX systems, enter the following commands:
```
>>> D/I 14 C
>>> CONT
IPC> 
```
  The first command tells the hardware to generate a software interrupt at level C (#12).
- On Alpha systems, enter the following commands:
```
>>> D SIRR C
>>> CONT
IPC> 
```

To exit from IPC, press Ctrl/Z:
```
IPC> Ctrl/Z
```

Recalculating Quorum

You can enter the following commands at the console to recalculate quorum:

On VAX systems:

>>> D/I 14 C
>>> CONT
IPC> Q 
IPC> Ctrl/Z

On Alpha systems, enter the following commands:

>>> D SIRR C
>>> CONT
IPC> Q 
IPC> Ctrl/Z

Although IPC Q commands recalculate quorum in an OpenVMS Cluster, do not use these commands. Instead, use either of the following to recalculate cluster quorums:

On OpenVMS VAX systems, DECamds

On OpenVMS Alpha systems, the Availability Manager

Canceling Mount Verification

To cancel mount verification using IPC, enter the following command from the console terminal in response to the IPC> prompt:

IPC> C device-name

This command cancels any pending mount verification on the device specified. (A warning is given if no mount verification was in progress for that device.) For example:

IPC> C MUA1:

When a pending mount verification is canceled, OPCOM prints a message in the following format:

%%%%%%%%%%% OPCOM, <dd-mmm-yyyy hh:mm:ss.cc> %%%%%%%%%%%
Mount verification aborted for device <device-name.

After you successfully cancel a pending mount verification using this technique, you must dismount and then remount the volume before you can access it again.

Examples

%%%%%%%%%%% OPCOM, 28-MAY-2000 10:54:54.12 %%%%%%%%%%%
        Device DUA0: is offline.
        Mount verification in progress.

On VAX systems, you might enter the following commands:

$ Ctrl/P 
.
.
.
>>> D/I 14 C
>>> CONT
IPC> C DUA0:
IPC> Ctrl/Z
%SYSTEM-I-MOUNTVER, _DUA0: has aborted mount verification.
%%%%%%%%%%% OPCOM, 28-MAY-2000 10:56:26.13 %%%%%%%%%%%
Mount verification aborted for device DUA0:

On Alpha systems, you might enter the following commands:

$ Ctrl/P 
.
.
.
>>> D SIRR C
>>> CONT
IPC> C DUA0:
IPC> Ctrl/Z
%SYSTEM-I-MOUNTVER, _DUA0: has aborted mount verification.
%%%%%%%%%%% OPCOM, 28-MAY-2000 10:56:26.13 %%%%%%%%%%%
Mount verification aborted for device DUA0:

In both examples, device DUA0: is off line, but you are unable to spin the disk back up. No other drive is available on the controller, so you cannot switch the unit select plugs of the two drives.

Do not enter a DISMOUNT command for the disk because it was mounted as a private volume, and you do not have access to it. The %SYSTEM-I-MOUNTVER message also appears because this is the console terminal.

Entering the Debugger

To use the XDELTA debugger, enter the following commands from the console terminal:

IPC> X

You are now in the debugger. The X command transfers control to the debugging tool XDELTA (provided it was loaded with the system by setting the appropriate value in the boot file). If XDELTA has not been loaded, the prompt IPC> is reissued. For example:

IPC> X
IPC>

To exit from the debugger, press Ctrl/Z:

 Ctrl/Z

For information about the XDelta debugger, refer to the OpenVMS Debugger Manual.

Using Mount Verification for Recovery

Using the Bad Block Locator Utility to Detect Media Errors