DIGITAL Software Product Description ___________________________________________________________________ PRODUCT NAME: DECram for OpenVMS Version 2.2B SPD 34.26.05 DESCRIPTION DECram for OpenVMS Version 2.2B supports both the OpenVMS for Alpha and OpenVMS for VAX platforms. DECram for OpenVMS is a disk device driver that improves I/O performance 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 software. 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 DECram for OpenVMS Version 2.2B is fully supported when installed on any valid and licensed standalone or clustered VAX or Alpha system. DECram devices can be members of a shadow set, and can be served by mass storage control protocol (MSCP). There are no special hardware requirements to install DECram for OpenVMS Version 2.2B. July, 1996 AE-PFM1F-TE 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 device type DT$_RAM_DISK is not known by the SHOW DEVICE command in current 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 DIRECTORY commands will work the same on both hard disk and DECram devices. However, the standard utilities are used differently to set up a DECram device. System Analysis Before creating a DECram device, the OpenVMS system manager must determine 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 below. 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 2.2B currently has the following restrictions: o Data in a DECram device is volatile. o A single DECram device size is limited to 524,280 blocks. Note: For disk volumes larger than 524,280 blocks, multiple DECram disk devices can be created and bound into a volume set. 2 DECram for OpenVMS is not designed to support long-term data storage. If a system or hardware failure occurs, data stored in the DECram device is lost and must be re-created. HARDWARE REQUIREMENTS Processor and hardware configurations as specified in the OpenVMS Operating 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 2.2B supports OpenVMS for Alpha Operating System Version 6.1 or higher. DECram for OpenVMS Version 2.2B supports OpenVMS for VAX Operating System Version 6.1 or higher. ORDERING INFORMATION OpenVMS for VAX Software Licenses: QL-GJ9A*-** Software Media: QA-YL48A-HA Software Product Services: QT-GJ9A*-** This product (OpenVMS for VAX) is distributed on the consolidated OpenVMS for VAX Layered Product Compact Disk (order number QA-YL48A-H8). OpenVMS for Alpha Software Licenses: QL-MV3A*-** Software Media: QA-03XAA-H8 Software Product Services: QT-MV3A*-** * Denotes variant fields. For additional information on available licenses, services, and media, refer to the appropriate price book. 3 This product (OpenVMS for Alpha) is distributed on the consolidated OpenVMS for Alpha Layered Product Compact Disk (order number QA-03XAA-H8). DECram for OpenVMS documentation is available in Bookreader, text, and PostScript[R] formats. SOFTWARE LICENSING This software is furnished under the licensing provisions of Digital Equipment Corporation's Standard Terms and Conditions. For more information about Digital's licensing terms and policies, contact your local Digital office. License Management Facility Support This layered product supports the OpenVMS License Management Facility. 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 Description (SPD 25.01.xx), or the appropriate operating system documentation set. SOFTWARE PRODUCT SERVICES A variety of service options are available from Digital. For more information, contact your local Digital office. SOFTWARE WARRANTY Warranty for this software product is provided by Digital with the purchase of a license for the product as defined in the Software Warranty Addendum of this SPD and the applicable Digital Standard Terms and Conditions. 4 [R] PostScript is a registered trademark of Adobe Systems Incorporated [TM] Bookreader, the DIGITAL Logo, Digital, MSCP, OpenVMS, OpenVMS Cluster, TK, VAX, VAXcluster, VMS, and VMScluster are trademarks of Digital Equipment Corporation. © 1996 Digital Equipment Corporation. All rights reserved. 5