DECram for OpenVMS Release Notes

DECram for OpenVMS Release Notes

January 1999

This document describes issues that pertain to Version 2.3 of DECram for OpenVMS.

Revision/Update Information This document supersedes all previous versions of DECram for VMS Release Notes.

Operating System and Version: OpenVMS VAX Version 6.2 or higher, OpenVMS Alpha Version 6.2 or higher

Software Version: DECram for OpenVMS Version 2.3

Compaq Computer Corporation
Houston, Texas

January 1999

Compaq Computer Corporation makes no representations that the use of its products in the manner described in this publication will not infringe on existing or future patent rights, nor do the descriptions contained in this publication imply the granting of licenses to make, use, or sell equipment or software in accordance with the description.

Possession, use, or copying of the software described in this publication is authorized only pursuant to a valid written license from Compaq or an authorized sublicensor.

Compaq conducts its business in a manner that conserves the environment and protects the safety and health of its employees, customers, and the community.

© Compaq Computer Corporation 1999. All rights reserved.

The following are trademarks of Compaq Computer Corporation: Alpha, Compaq, DECdirect, DIGITAL, OpenVMS, VAX, VAX DOCUMENT, VAXcluster, VMS, and the Compaq logo.

The following are third-party trademarks:

POSTSCRIPT is a registered trademark of Adobe Systems Incorporated.

All other trademarks and registered trademarks are the property of their respective holders.


The DECram documentation set is available on CD-ROM.



There are currently no known problems that pertain to Version 2.3 of DECram for OpenVMS.

The user should be familiar with DECram for OpenVMS and its associated manuals: DECram for OpenVMS User's Manual and DECram for OpenVMS Installation Guide.

Chapter 1
System Manager Release Notes

This chapter contains information about DECram for OpenVMS for the system manager.

1.1 Changes in DECram for OpenVMS Version 2.3

Most of the changes apply to OpenVMS Alpha systems only. Thus, the vast majority of VAX users will not need to upgrade to this version.

1.2 DECram for OpenVMS Version 2.3 Required for OpenVMS Alpha Systems

DECram for OpenVMS Version 2.3 is the minimum supported version of DECram when used on systems running OpenVMS Alpha Version 7.2 (and higher). It is also required for any OpenVMS Cluster systems running any version of OpenVMS Alpha.

Previous versions of DECram must not be used if DECram disks are being served, or served and shadowed across nodes within the cluster, or if DECram is being used in an Adaptive Partitioned Multiprocessing (APMP) instance. (An Adaptive Partitioned Multiprocessing instance is often referred to as Galaxy.)

1.2.1 Support for APMP Systems

DECram for OpenVMS Version 2.3 is the first version of DECram that supports operation in an Adaptive Partitioned Multiprocessing environment.

1.2.2 Increase in Maximum DECram Disk Size

DECram for OpenVMS Version 2.3 allows the creation of larger DECram disks than previously possible. Earlier DECram versions limited the DECram disk to 524280 pagelets (disk blocks). This limit has been extended to 32 Gb on OpenVMS Alpha Version 7.0 and higher. Because VAX memory space is architecturally limited, the limit of 524280 pagelets (disk blocks) remains in effect for OpenVMS VAX systems.

A DECram disk can only be created if there are sufficient system resources available---the primary one being physical memory itself. DECram will display error messages if attempts are made to allocate more resources than are available.

1.2.3 Shadowing to Physical Media

DECram for OpenVMS Version 2.3 has also been modified so that the DECram disk that is created by an INIT/SIZE=xxxxxxx will have exactly xxxxxxx blocks. This change makes it possible to shadow the DECram disk to a physical disk, thereby providing data integrity in the event of power loss or other failure at a relatively low cost in performance for most users.

Volume Shadowing for OpenVMS required a number of modifications to support this capability. For example, it had to determine that all reads should come from DECram devices rather than from physical devices for performance reasons.

To use the new functionality of shadowing DECram disks to physical disks, you must apply the Volume Shadowing for OpenVMS remedial kit that includes these changes. Contact your Compaq service representative to obtain the appropriate remedial kit. OpenVMS Version 7.2 does not contain this functionality. However, future releases are expected to include these changes.


Do not attempt to shadow DECram disks to physical disks without installing the new Volume Shadowing for OpenVMS remedial kit. Serious data integrity problems could occur without the remedial kit.


DECram for OpenVMS Version 2.3 prevents the possible occurrence of a rare SSRVEXCEPT crash in DECRAM$RECOVER.EXE during system startup for OpenVMS Alpha Version 6.2 or higher.

The problem has been rectified by modifying the startup sequence. The file DECRAM$EXECLET.EXE has been removed from the kit. For systems currently using DECram, the installation procedure will disable the running of this image at system startup but will not delete the file. You can manually delete SYS$SPECIFIC:[SYSLDR]DECRAM$EXECLET.EXE if you wish. All functionality of the DECRAM$EXECLET has been added to the new DECRAM$RECOVER.EXE image, which will be added to your system startup database in the INITIAL phase, as shown in the following example:

%SYSMAN-I-COMFIL, contents of component database on node VEAL 
Phase        Mode   File 
------------ ------ --------------------------------- 

Compaq recommends that you delete all files named DECRAM$EXECLET.EXE on OpenVMS Alpha systems.

1.3 Known Problems with Earlier Versions of OpenVMS

The following problems exist when DECram for OpenVMS Version 2.3 is run on earlier versions of OpenVMS. These problems do not exist when DECram for OpenVMS Version 2.3 is run on OpenVMS Version 7.2.

1.3.1 Possible Erroneous Error Message During Device Initialization

If the user attempts to initialize a DECram device using the INITIALIZE command and does not have VOLPRO privilege, the system returns the following incorrect error message:

%INIT-F-INTDIV, arithmetic trap, integer divide by zero at PC=xxxxxxxx 
The correct message that the system should return is:

%SYSTEM-F-NOPRIV, no privilege for attempted operation 

1.3.2 DECram Device Type Unknown to OpenVMS Systems

The response to the SHOW DEVICES/FULL command indicates device type unknown with OpenVMS Alpha Version 6.1, OpenVMS VAX Version 6.1, and subsequent versions. The device type DT$_RAM_DISK is not currently known by the SHOW DEVICES command in OpenVMS Alpha Version 6.1, OpenVMS VAX Version 6.1, and subsequent versions.


If resources are allocated, the system returns the following response:

Disk MDA0:, device type unknown, is online, file-oriented device, 
Error count              0    Operations completed             137815 
Owner process           ""    Owner UIC                         [0,0] 
Owner process ID  00000000    Dev Prot    S:RWED,O:RWED,G:RWED,W:RWED 
Reference count          0    Default buffer size                 512 
Total blocks           304    Sectors per track                     1 
Total cylinders         38    Tracks per cylinder                   8