Compaq Software Product Description ___________________________________________________________________ PRODUCT NAME: DECram for OpenVMS Version 2.3 SPD 34.26.07 Compaq Software Product Description ___________________________________________________________________ PRODUCT NAME: DECram for OpenVMS Version 2.3 SPD 34.26.07 DESCRIPTION DECram for OpenVMS Version 2.3 supports both the OpenVMS for Alpha and OpenVMS for VAX platforms. DECram for OpenVMS is a disk device driver that improves I/O perfor- mance by allowing an OpenVMS system manager to create pseudo disks (RAMdisks), which reside in main memory. Frequently accessed data can be accessed much faster from a DECram device than from a physical disk device. These RAMdisks can be accessed through the file system just as physical disks are accessed, requiring no change to the application or the system soft- ware. Because main memory is allocated for a DECram device, extra memory is generally required. The OpenVMS system manager can designate the amount of memory dedicated to the DECram device(s) and the files that will be stored on it. Cluster Environment January, 1999 DECram for OpenVMS Version 2.3 is fully supported when installed on any valid and licensed standalone Alpha or VAX system, or any clus- tered VAX system. DECram for OpenVMS Version 2.3 is required for any OpenVMS Cluster systems running any version of OpenVMS Alpha. DECram for OpenVMS Version 2.3 supports operation in an Adaptive Par- titioned Multi-Processing (APMP) environment, also known as Compaq Galaxy Software Architecture on OpenVMS. Previous versions of DECram must not be used if RAM disks are being served, or served and shadowed, across nodes within a cluster, or if DECram is being used in an Adaptive Par- titioned Multi-Processing instance. Multiple DECram devices can be members of a Volume Shadowing for Open- VMS shadow set and can be served by mass storage control protocol (MSCP). There are no special hardware requirements to install DECram for Open- VMS Version 2.3. User Interface The user interface to a DECram device is the same as other disk class devices. Note that the response to a SHOW DEVICE /FULL command will indicate "device type unknown" in current OpenVMS releases. The de- vice type DT$_RAM_DISK is not known by the SHOW DEVICE command in cur- rent OpenVMS releases. Management Interface A DECram device is managed by the same tools used to manage any other OpenVMS disk device. For example, the INITIALIZE, MOUNT, and DIREC- TORY commands will work the same on both hard disk and DECram devices. However, the standard utilities are used differently to set up a DE- Cram device. System Analysis Before creating a DECram device, the OpenVMS system manager must de- termine its size. Each disk block allocated to a DECram device will mean one less page of available memory. The system manager should also assess the need for multiple DECram units. See Restrictions listed be- low. 2 System Generation When adding a DECram device, the OpenVMS system manager must reassess the values for the SYSGEN parameters that control paging and swapping behavior. Restrictions DECram for OpenVMS Version 2.3 currently has the following restric- tions: o Data in a DECram device is volatile. o Volume Shadowing for OpenVMS will support shadow sets composed of DECram devices and other disk class devices, in a future release. Removal of the last non DECram device will cause the shadow set vir- tual unit to abort and become unavailable. Please refer to the Vol- ume Shadowing for OpenVMS Software Product Description (SPD 27.29.xx) for more information. o A single DECram device size on OpenVMS Alpha systems running Ver- sion 7.1 or higher is limited to 32GB. o A single DECram device size on OpenVMS VAX systems running Version 6.2 or higher is limited to 524,280 blocks. Note: For disk volumes larger than 524,280 blocks on VAX or 32GB on Al- pha, multiple DECram disk devices can be created and bound into a vol- ume set. DECram for OpenVMS is not designed to support long-term data storage. If a system or hardware failure occurs, data stored in the DECram de- vice is lost and must be re-created. This restriction does not apply if the device is shadowed to a real physical device, using a supported version of OpenVMS Volume Shadowing. 3 YEAR 2000 READINESS This product is capable of accurately processing, providing, and/or receiving date data from, into and between the twentieth and the twenty- first centuries, and the years 1999 and 2000, including leap year cal- culations, when used in accordance with the associated product doc- umentation and provided that all hardware, firmware and software used in combination with the product properly exchange accurate date data with the product. HARDWARE REQUIREMENTS Processor and hardware configurations as specified in the OpenVMS Op- erating System Software for VAX and Alpha Product Description (SPD 25.01.xx), or the appropriate operating system documentation set. SOFTWARE REQUIREMENTS DECram for OpenVMS Version 2.3 supports OpenVMS for Alpha Operating System Version 7.1 or higher. DECram for OpenVMS Version 2.3 is also required for any OpenVMS Cluster systems running any version of Open- VMS Alpha. DECram for OpenVMS Version 2.3 supports OpenVMS for VAX Operating Sys- tem Version 6.2 or higher. ORDERING INFORMATION OpenVMS for VAX Software Licenses: QL-GJ9A*-** Software Media: QA-YL48A-H8 Software Product Services: QT-GJ9A*-** DECram for OpenVMS Version 2.3 (for VAX) is distributed on the Open- VMS VAX Software Product Library Distribution CD-ROMs (order number QA-YL48A-H8). 4 DECram is no longer available on TK50 and magtape media. OpenVMS for Alpha Software Licenses: QL-MV3A*-** Software Media: QA-03XAA-H8 Software Product Services: QT-MV3A*-** DECram for OpenVMS Version 2.3 (for Alpha) is distributed on the Open- VMS Alpha Software Product Library Distribution CD-ROMs (order num- ber QA-03XAA-H8). * Denotes variant fields. For additional information on available li- censes, services, and media, refer to the appropriate price book. DECram for OpenVMS documentation is available in Bookreader, text, and PostScript[R] formats. SOFTWARE LICENSING This software is furnished under the licensing provisions of Compaq Computer Corporation's Standard Terms and Conditions. For more infor- mation about Compaq's licensing terms and policies, contact your lo- cal Compaq office. License Management Facility Support This layered product supports the OpenVMS License Management Facil- ity. License units for this product are allocated on a CPU-capacity basis. For more information on the License Management Facility, refer to the OpenVMS Operating System for VAX and Alpha Software Product Descrip- tion (SPD 25.01.xx), or the appropriate operating system documenta- tion set. 5 SOFTWARE PRODUCT SERVICES A variety of service options are available from Compaq. For more in- formation, contact your local Compaq office. SOFTWARE WARRANTY This software is provided by Compaq with a 90 day conformance warranty in accordance with the Compaq warranty terms applicable to the license purchase. [R] PostScript is a registered trademark of Adobe Systems Incor- porated [TM] Bookreader, the Compaq Logo, Compaq, MSCP, OpenVMS, Open- VMS Cluster, TK, VAX, VAXcluster, VMS, and VMScluster are trademarks of Compaq Computer Corporation. © 1998 Compaq Computer Corporation. All rights reserved. 6