DIGITAL Software Product Description ___________________________________________________________________ PRODUCT NAME: StorageWorks RAID Software SPD 46.49.05 for OpenVMS, Version 2.4 DESCRIPTION StorageWorks[R] RAID Software for OpenVMS[R] is a software product that uses RAID technology to manage groups of disk drives as arrays. The product supports RAID Level 0 arrays (Disk striping) for enhanced I/O performance and RAID Level 5 arrays (Disk striping with parity) for enhanced data availability on both VAX[R] and Alpha platforms. RAID Software also allows partitioning or segmentation of a RAID Array into multiple virtual devices. StorageWorks RAID Software for OpenVMS Capabilities and Features StorageWorks RAID Software for OpenVMS manages groups of between 1 and 32 physical disks (between 3 and 32 for RAID Level 5) as arrays. Ap- plications use a virtual disk as if it were a physical disk. A total of 50 such arrays per VMScluster system are supported, in any mixture of RAID Level 0 and RAID Level 5. StorageWorks RAID virtual disks may be accessed directly from any mem- ber of a VMScluster system for which a valid license is in effect. (All VMScluster systems may access virtual disks created using the Stor- age Concurrent Use license QL-0MGAA-3B.) Virtual disks may not be MSCP[R] served. The disks in a StorageWorks RAID Software for OpenVMS array may be of different types, although disks of a single type are recommended for consistent performance and optimal use of storage capacity. April 1997 AE-Q1GDG-TE StorageWorks RAID Software for OpenVMS virtual disks may not be used to boot the OpenVMS Operating System, nor may they serve as VMSclus- ter quorum disks. They may, however, contain OpenVMS page and swap files. StorageWorks RAID Software for OpenVMS may be used in conjunction with OpenVMS Volume Shadowing (Phase II only). OpenVMS shadow sets may be StorageWorks 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. Single-member shadow sets may also be used as RAID array members so that the VAXsimPLUS autocopy feature may be employed as a failure pro- tection mechanism. 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. 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 2 o higher data transfer rate due to concurrent transfer of data to or from more than one disk to satisfy a single request. 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. StorageWorks 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, Stor- ageWorks RAID Software for OpenVMS provides continued service to ap- plications 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, StorageWorks RAID Software for OpenVMS software can be used in conjunction with redun- dant hardware and supporting software throughout 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. StorageWorks RAID Software for OpenVMS reconstructs the contents of a failed disk if a replacement disk is assigned to it. Reconstruction does not interrupt application access to data on the array, although performance may be affected. Replacement disks may either be assigned to StorageWorks RAID Software for OpenVMS by the storage administra- tor (using a DCL command) or they may be placed in a spareset asso- ciated with one or more RAID Level 5 arrays. If a disk in a RAID Level 5 array with an associated spareset fails, StorageWorks RAID Software for OpenVMS automatically acquires a replacement disk from the spare- set and performs reconstruction without storage administrator inter- vention. 3 Using StorageWorks RAID Software for OpenVMS To use StorageWorks RAID Software for OpenVMS, the storage adminis- trator first creates an array using DCL functions supplied with the software. This destroys any data previously stored on the disks and creates the data structures required to manage the array. The member disks of a StorageWorks RAID Software for OpenVMS array are ODS-2 struc- tured volumes, so OpenVMS mechanisms protect against inadvertent mis- use of members for the life of the array. Each virtual disk created by StorageWorks RAID Software for OpenVMS is a single management entity. The storage administrator should use appropriate storage management procedures (e.g., backups) with vir- tual disks, which can be considerably larger than typical physical disks. Once a collection of physical disks is bound into an array, it is not possible to retrieve data directly from the array's individual mem- ber disks. Performance of StorageWorks RAID Software for OpenVMS The primary purpose of StorageWorks RAID for OpenVMS RAID Level 0 ar- rays is to enhance application performance by improving I/O request processing and/or data transfer rate. RAID Level 0 technology normally implies a reduction in data reliability. The storage administrator can improve data reliability by increasing backup frequency or using Stor- ageWorks RAID Software for OpenVMS in conjunction with Volume Shad- owing for OpenVMS. The primary purpose of StorageWorks 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 applica- tions whose I/O workload consists largely of reading data. For appli- cations with mostly write I/O workloads, StorageWorks RAID Software for OpenVMS RAID Level 5 arrays may provide lower I/O performance than conventional disks because it must update redundant information each time an application writes data. 4 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 StorageWorks RAID Soft- ware for OpenVMS is appropriate for use with a given application. HARDWARE REQUIREMENTS StorageWorks RAID Software for OpenVMS is supported when used with the VAX and Alpha processors and VMScluster systems supported by OpenVMS. See the Software Requirements section for the supported OpenVMS ver- sions. StorageWorks RAID Software may be installed in a VMScluster con- figuration of any size supported by OpenVMS Software, but the Stor- ageWorks RAID Software has been qualified to run on a maximum of 20 nodes within a single VMScluster configuration. StorageWorks 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 VMSclus- ter system. Disks, storage elements, (and the subsystem configurations that contain them) are supported by the OpenVMS Operating System Ver- sions listed above through the following device drivers shown in Ta- ble 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___________________________________________ 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 StorageWorks RAID Software for OpenVMS requires the OpenVMS VAX Op- erating System (Version 5.5, 5.5-1, 5.5-2, 6.0, 6.1, 6.2, 7.0,and 7.1) or OpenVMS Alpha (Versions 1.5, 6.1, 6.2, 7.0 and 7.1) as a prereq- uisite. No other prerequisite software is required. 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 supported by StorageWorks RAID Software. For a chart of the compatible versions of the operating systems, refer to the VAXcluster Software for OpenVMS VAX Software Product Description (SPD 29.78.xx) and the VMScluster Soft- ware for OpenVMS Alpha Software Product Description (SPD 42.18.xx). In order to bind StorageWorks RAID arrays, all physical disks that com- prise the RAID arrays must be accessible, (local or MSCP served), on all nodes in a VMScluster having the RAID software running. 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 StorageWorks RAID Software. Shadow sets may not be used as members of RAID Level 5 arrays. 6 DISTRIBUTION MEDIA TK50 Streaming Tape 1600 bpi Magtape This layered product is also 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 Two 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 StorageWorks RAID Software for OpenVMS on a single VAX or Alpha sys- tem to create and use up to the supported number (50) of RAID arrays. One RAID Array Access License is required for each VAX or Alpha sys- tem in a VMScluster system on which StorageWorks RAID Software for Open- VMS 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 StorageWorks RAID Software for Open- VMS array. Once an array is created, it may be accessed by any VMSclus- ter VAX or Alpha system. 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 7 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. Media: VAX: QA-0MGAA-H5 VAX: QA-0MGAA-HM 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. StorageWorks RAID Software V2.4, and continuing with future releases, the right to use the RAID Level 0 function of the StorageWorks RAID Software is included in the license for POLYCENTER Striping for Open- VMS VAX. This applies to OpenVMS VAX installations only as POLYCEN- TER Striping operates solely on that platform. When an Update License is required for StorageWorks RAID Software and the license that granted the right to use the product is POLYCENTER Striping, the customer should purchase the POLYCENTER Striping Update License. For more information about Digital's licensing terms and conditions, contact your local Digital office. License Management Facility Support 8 StorageWorks RAID Software for OpenVMS software uses the OpenVMS Li- cense Management Facility. License Units for the StorageWorks RAID Software for OpenVMS RAID Ar- ray Access License are allocated on a CPU-capacity basis. License Units for the StorageWorks 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 included in an array, no matter how many VMScluster CPUs have access to the array. 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 Dig- ital. For more information, contact your local Digital office. SOFTWARE WARRANTY Warranty of this software is provided by Digital with the purchase of license for the product as defined in the Software Warranty Addendum of this SPD. [TM]The Digital logo, DEC, Digital, MSCP, OpenVMS, StorageWorks, TK, VAX, and VMScluster are trademarks of Digital Equipment Corporation. All other trademarks and registered trademarks are the property of their respective holders. © 1997 Digital Equipment Corporation. All rights reserved. 9