COMPAQ Software Product Description ___________________________________________________________________ PRODUCT NAME: Compaq RAID Software SPD 46.49.08 for OpenVMS, Version 2.5 DESCRIPTION Compaq RAID Software for OpenVMS[R] is a software product that uses RAID technology to manage groups of disk drives as arrays. The prod- uct supports RAID Level 0 arrays (Disk striping) for enhanced I/O per- formance and RAID Level 5 arrays (Disk striping with parity) for en- hanced data availability on both VAX and Alpha platforms. RAID Soft- ware also allows partitioning or segmentation of a RAID Array into mul- tiple virtual devices. RAID Software for OpenVMS Capabilities and Features RAID Software for OpenVMS manages groups of between 1 and 32 physi- cal disks (between 3 and 32 for RAID Level 5) as arrays. Applications use a virtual disk as if it were a physical disk. A maximum of 50 such arrays per VMScluster system are supported, in any mixture of RAID Level 0 and RAID Level 5. RAID virtual disks may be accessed directly from any member of a VM- Scluster system for which a valid license is in effect. (All VMSclus- ter systems may access virtual disks created using the Storage Con- current Use license QL-0MGAA-3B.) Virtual disks may not be MSCP[R] served. The disks in a RAID Software for OpenVMS array may be of different types, although disks of a single type are recommended for consistent per- formance and optimal use of storage capacity. October 2001 AE-Q1GDK-TE RAID Software for OpenVMS virtual disks may not be used to boot the OpenVMS Operating System, nor may they serve as VMScluster quorum disks. They may, however, contain OpenVMS page and swap files. RAID Software for OpenVMS may be used in conjunction with OpenVMS Vol- ume Shadowing (Phase II only). OpenVMS shadow sets may be made up of RAID Software for OpenVMS array members (RAID Level 0 only), however, virtual disks may not be members of OpenVMS shadow sets. A RAID Level 0 array whose members are shadow sets is a high perfor- mance, high data availability storage solution for most applications. Partitioning is the process of dividing a RAID array into one or more RAID virtual devices. The RAID Software allows you to specify how many partitions are to be used in a given RAID array and how large each par- tition should be. One or more partitions can be created on a single- member RAID Level 0 array or multiple-member RAID Level 0 or RAID Level 5 arrays. The maximum number of partitions for any array is 64. The maximum size of one array is 1 TB. Features Applicable to RAID Level 0 Arrays The usable capacity of RAID Level 0 array is approximately given by: Usable Capacity = N * 0.99 * CS Where N is the number of physical disks in the array. CS is the storage capacity of the smallest disk in the array. The purpose of RAID Level 0 technology is to provide I/O intensive ap- plications with greater I/O performance from a given I/O hardware con- figuration than would normally be achieved by using the disks as in- dividual volumes. This is also referred to as Disk Striping. Depend- ing on the application, enhanced I/O performance may be delivered as: o more I/O requests serviced per unit time due to probabilistic load balancing, or o higher data transfer rate due to concurrent transfer of data to or from more than one disk to satisfy a single request. 2 Features Applicable to RAID Level 5 Arrays The usable capacity of RAID Level 5 array is approximately given by: Usable Capacity = (N-1) * 0.99 * CS Where N is the number of physical disks in the array. CS is the capacity of the smallest disk in the array. RAID Software for OpenVMS protects against loss of data and loss of data accessibility due to the failure of any single disk in a RAID Level 5 array. If a disk in a RAID Level 5 array fails, RAID Software for OpenVMS provides continued service to applications by regenerating the failed disk's data using information from the array's remaining disks. (For full protection against loss of data availability due to single hardware failures, RAID Software for OpenVMS software can be used in conjunction with redundant hardware and supporting software through- out the system.) While a RAID Level 5 array is reduced by a failed disk, data can be read and written, but no redundancy is provided. A second disk fail- ure while an array is reduced prevents application access to the data stored on the array, and may result in data loss. RAID Software for OpenVMS reconstructs the contents of a failed disk if a replacement disk is assigned to it. Reconstruction does not in- terrupt application access to data on the array, although performance may be affected. Replacement disks may either be assigned to RAID Soft- ware for OpenVMS by the storage administrator (using a DCL command) or they may be placed in a spareset associated with one or more RAID Level 5 arrays. If a disk in a RAID Level 5 array with an associated spareset fails, RAID Software for OpenVMS automatically acquires a re- placement disk from the spareset and performs reconstruction without storage administrator intervention. Using RAID Software for OpenVMS 3 To use RAID Software for OpenVMS, the storage administrator first cre- ates an array using DCL functions supplied with the software. This de- stroys any data previously stored on the disks and creates the data structures required to manage the array. The member disks of a RAID Software for OpenVMS array are ODS-2 structured volumes, so OpenVMS mechanisms protect against inadvertent misuse of members for the life of the array. However, the virtual disk units created by RAID Soft- ware can be initialized as FILES-11 ODS2 or ODS5 or any other volume structure. Each virtual disk created by RAID Software for OpenVMS is a single man- agement entity. The storage administrator should use appropriate stor- age management procedures (e.g., backups) with virtual disks, which can be considerably larger than typical physical disks. Once a col- lection of physical disks is bound into an array, it is not possible to retrieve data directly from the array's individual member disks. Performance of RAID Software for OpenVMS The primary purpose of RAID for OpenVMS RAID Level 0 arrays is to en- hance application performance by improving I/O request processing and /or data transfer rate. RAID Level 0 technology normally implies a re- duction in data reliability. The storage administrator can improve data reliability by increasing backup frequency or using RAID Software for OpenVMS in conjunction with Volume Shadowing for OpenVMS. The primary purpose of RAID Software for OpenVMS RAID Level 5 arrays is to improve data reliability. It may provide the secondary benefit of improved performance (due to load balancing) for applications whose I/O workload consists largely of reading data. For applications with mostly write I/O workloads, RAID Software for OpenVMS RAID Level 5 ar- rays may provide lower I/O performance than conventional disks because it must update redundant information each time an application writes data. The storage administrator should understand application I/O charac- teristics and weigh the relative priorities of performance, equipment cost, and data reliability to determine whether RAID Software for Open- VMS is appropriate for use with a given application. 4 HARDWARE REQUIREMENTS RAID Software for OpenVMS is supported when used with the VAX and Al- pha processors and VMScluster systems supported by OpenVMS. See the Software Requirements section for the qualified OpenVMS versions. RAID Software may be installed in a VMScluster configuration of any size supported by OpenVMS Software, but the RAID Software has been qual- ified to run on a maximum of 20 nodes within a single VMScluster con- figuration. RAID Software for OpenVMS requires a minimum of 1 (for RAID Level 0) or 3 (for RAID Level 5) and a maximum of 32 physical disks for each array. Up to 50 arrays may be created in a single VMScluster system. Disks, storage elements, (and the subsystem configurations that con- tain them) are supported by the OpenVMS Operating System Versions listed above through the following device drivers shown in Table 1. ___________________________________________________________________ Table_1:_Supporting_Device_Drivers_________________________________ Device Drivers___Description______________________________________________ DUDRIVER For Digital Storage Architecture (DSA) disks, including MSCP-served Disks. DKDRIVER For SCSI disks DRDRIVER For StorageWorks RAID Array 200 series controllers, also known as SWXCR DKQDRIVER_For_HGx_connected_disks__________________________________ 5 ___________________________________________________________________ Table_2:_Disk_Space_Requirements___________________________________ Disk_Space_______VAX-based_________Alpha-based_____________________ During instal- 3500 blocks 5000 blocks (2.44 megabytes) lation (1.70 megabytes) For permanent 2500 blocks 4000 blocks (1.85 megabytes) use______________(1.22_megabytes)__________________________________ SOFTWARE REQUIREMENTS RAID Software for OpenVMS requires the OpenVMS VAX Operating System (Version 5.5-2, 6.2, 7.1, 7.2 and 7.3) or OpenVMS Alpha (Versions 6.2, 7.1-2, 7.2-1, 7.2-2 and 7.3) as a prerequisite. No other prerequisite software is required. RAID Software Version V2.5 will be the last ver- sion to qualify OpenVMS VAX version 5.5-2. Mixed-architecture VMScluster systems (i.e. containing both VAX and Alpha systems) are supported as long as all VMScluster members are run- ning compatible versions of the OpenVMS operating system qualified by RAID Software. For a chart of the compatible versions of the operat- ing systems, refer to the VAXcluster Software for OpenVMS VAX Soft- ware Product Description (SPD 29.78.xx) and the VMScluster Software for OpenVMS Alpha Software Product Description (SPD 42.18.xx). RAID Software for OpenVMS is compatible with OpenVMS 7.2-* and 7.3 with the following restrictions: SYSGEN Parameter MSCP_SERVE_ALL bit 3 must be set to prevent the serv- ing of Host Based Raidsets to other members of the cluster. Bit 3 en- ables the pre-V7.2 behavior of not serving Raidsets to other cluster members. In order to bind RAID arrays, all physical disks that comprise the RAID arrays must be accessible, (local or MSCP served), on all nodes in a VMScluster having the RAID software running. 6 If RAID Level 0 arrays with OpenVMS shadow sets as members are required, a valid OpenVMS Volume Shadowing license must be in effect on every VMScluster node running the RAID Software. Shadow sets may not be used as members of RAID Level 5 arrays. DISTRIBUTION MEDIA This layered product is only available as part of the OpenVMS Consol- idated Software Distribution on CD-ROM for VAX (QA-VWJ8A-A8) and on the Digital CD-ROM Software Library for OpenVMS Alpha (QA-03XAA-H8). ORDERING INFORMATION Three licensing options are available: RAID Array Access License: VAX: QL-0MHA*-AA Alpha: QL-2YFA*-AA This license option provides the purchaser with the right to use the RAID Software for OpenVMS on a single VAX or Alpha system to create and use up to the supported number (50) of RAID arrays. One RAID Ar- ray Access License is required for each VAX or Alpha system in a VM- Scluster system on which RAID Software for OpenVMS is to execute. Storage Concurrent Use License: QL-0MGAA-3B This license option provides the purchaser with the right to include a single disk, storage element, or shadow set in an array. One Stor- age Concurrent Use License is required for each disk, storage element, or shadow set to be included in a RAID Software for OpenVMS array. Once an array is created, it may be accessed by any VMScluster VAX or Al- pha system. 7 For purposes of the Storage Concurrent Use License, the measure of use is equal to a single disk, storage element, or shadow set to be in- cluded in an array, no matter how many VMScluster CPUs have access to that array. Each shadow set used as a member of a RAID Level 0 array requires a single Concurrent Use License, regardless of the number of physical disks in the shadow set. Disks, storage elements, and shadow sets that are members of spare- sets do not require Storage Concurrent Use Licenses. Documentation: VAX: QA-0MGAA-GZ Alpha: QA-0MGAA-GZ Software Product Services: Array Access (VAX): QT-0MHA*-** Array Access (Alpha): QT-2YFA*-** Storage: QT-0MGA*-** SOFTWARE LICENSING This software is furnished only under a license. For more information about Compaq licensing terms and conditions, con- tact your local Compaq office. License Management Facility Support RAID Software for OpenVMS software uses the OpenVMS License Manage- ment Facility. License Units for the RAID Software for OpenVMS RAID Array Access Li- cense are allocated on a CPU-capacity basis. License Units for the RAID Software for OpenVMS Storage Concurrent Use License are independent of CPU capacity. One Storage Concurrent Use License is required for each disk, storage element, or shadow set in- cluded in an array, no matter how many VMScluster CPUs have access to the array. 8 For more information on the License Management Facility, refer to the OpenVMS Operating System Software Product Description (SPD 25.01.xx) or the OpenVMS Operating System documentation. SOFTWARE PRODUCT SERVICES A variety of software product service options are available from Com- paq. For more information, 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. Compaq, the Compaq logo, VAX and VMS Registered in U.S. Patent and trade- mark Office. OpenVMS and Tru64 are trademarks of Compaq Information Technologies Group, L.P. in the United States and other countries. Motif and UNIX are trademarks of The Open Group in the United States and other countries. All other product names mentioned herein may be trademarks of their respective companies. Confidential computer software. Valid license from Compaq required for possession, use or copying. Consistent with FAR 12.211 and 12.212, Com- mercial Computer Software, Computer Software Documentation, and Tech- nical Data for Commercial Items are licensed to the U.S. government under vendor's standard commercial license. Compaq shall not be liable for technical or editorial errors or omis- sions contained herein. The information in this document is provided "as is" without warranty of any kind and is subject to change with- out notice. The warranties for Compaq products are set forth in the express limited warranty statements accompanying such products. Noth- ing herein should be construed as constituting an additional warranty. © 2001 Compaq Computer Corporation. All rights reserved. 9