OASAS I RELEASE 1.0 FOR IBM OS/2 Contents Announcement Letter Number 291-629 dated October 22, 1991 US - Last Revised on October 22, 1991 Brief Description of Announcement, Charges, and Availability OASAS I (1) Release 1.0, by Integra Technologies, Inc., is to be installed on Operating System/2 (R) (OS/2 (R)) Standard Edition (SE) Version 1.30.1 or later, the equivalent OS/2 SE 1.3 Corrective Service Diskette (CSD) level of 5015, or IBM OS/2 Version 2.0. OASAS I interfaces with an IBM SCSI adapter to manage a disk array ranging from three to seven IBM SCSI fixed disk drives. It provides fault-tolerant protection for a single fixed disk failure and gives the option of having the disk array drives appear as a single large volume to the operating system. Availability Date: October 22, 1991. (1) Registered trademark of Integra Technologies, Inc. (R) Registered trademark of International Business Machines Corporation. Customer Letter Section HIGHLIGHTS OASAS I, which is enabled for National Language support, includes the following functions: o Formatting an array of and operating, multiple drives; labeling single or multiple volumes; allowing the user to choose either the High Performance File System (HPFS) or the File Allocation Table (FAT) file system for the disk array file system, including the option to disable fault tolerance for customer environments where performance has priority over redundancy. o Striping of data, programs and error correction code across all drives. o Logging system events, recreating a down drive, monitoring drive status for errors and reporting error messages on the local system and to a remote workstation on a local area network (LAN); online help facilities. o Overlapping seeks for performance enhancement. o Correction for errors and defects in media. DESCRIPTION BUSINESS SOLUTIONS OASAS I is a product that manages an array of IBM SCSI fixed disk drives. This software provides 'data striping' and fault tolerance that can compensate for any single drive failure in the disk array, while granting continuous read/write operation to it. All of the OASAS I disk array device driver functions are transparent to the operating system. Updates to the error correction blocks are handled by the OASAS I disk array device driver. Additional overhead will be incurred by the host computer processor when this device driver generates the error correction code. OASAS I for use with IBM OS/2, by Integra Technologies, Inc., allows any IBM 160MB, 320MB or 400MB SCSI disk drive to be used as a fault-tolerant disk array in a 386-based Personal System/2 (R) (PS/2 (R)). (R) Registered trademark of International Business Machines Corporation. REDUNDANT ARRAYS OF INEXPENSIVE DISKS (RAID): Researchers at the University of California at Berkeley have provided solutions for the I/O bottleneck of the high-performance computer by introducing the concept of Redundant Arrays of Inexpensive Disks (RAID). Five RAID schemes provide data redundancy to increase reliability and provide parallel access to increase performance. Each scheme has its own characteristics. A summary of the five levels of RAID technology follows: o RAID level 1 -- mirrored disks: All the data from one disk is duplicated onto another. o RAID level 2 -- bit or block interleaved array (hamming code error correction): This solution 'stripes' data at the bit or byte level and uses multiple error correction drives. (Striping is a scheme that spreads data across the drives in the array.) o RAID level 3 -- single check disk per group: Similar to RAID level 2, but it only uses one drive for error correction and has synchronized head rotation. o RAID level 4 -- independent reads and writes: The same as RAID 3 except that it stripes the data at the sector level, rather than at the bit or byte level, and has un-synchronized head rotation. This solution is also known as 'data guarding.' o RAID level 5 -- spread data/parity over all disks (no single check disk): Similar to RAID level 4, except that it stores error correction/parity on all the drives in the array, rather than having a single dedicated parity drive. This removes the bottleneck that can occur with a single parity drive solution. The OASAS I Disk Array Management Software has implemented RAID level 5. GROWTH ENABLEMENT OASAS I enables a PS/2 to be upgraded from a single hard disk to multiple SCSI hard disks (three to seven). OASAS I enables the system to view the disk array as one large hard disk, allowing customers to keep large data bases on PS/2s that previously did not have this capability. OASAS I has a full set of utilities, enabling customers to install, format, log, scan, exercise and monitor the disk array. It also provides formatting the disk array to either the HPFS or the FAT file system, labeling of single or multiple volumes, operating multiple drives and reporting error messages. OASAS I is fully compatible with IBM OS/2 SE 1.30.1 or later capable systems and applications. OASAS I will also support IBM OS/2 2.0. PUBLICATIONS The publication for OASAS I is included as part of the program package and is not available separately. To order, contact your IBM representative. SCHEDULE The availability date is October 22, 1991. TECHNICAL INFORMATION SPECIFIED OPERATING ENVIRONMENT MACHINE REQUIREMENTS: The minimum hardware configuration for OASAS I Release 1.0 is as follows: o The minimum hardware required by IBM OS/2 SE 1.30.1 or later, the equivalent OS/2 SE 1.3 CSD level of 5015, or IBM OS/2 Version 2.0. For large single volume disk arrays, additional memory may be required by file system programs such as the OS/2 HPFS CHKDSK and CACHE programs. The OASAS I disk array device driver only consumes about 100K of memory. Use the IBM OS/2 SE documentation to determine the actual amount of memory required. o An IBM SCSI adapter (cached or non-cached) is required. An additional IBM SCSI adapter is needed if all of the drives for the disk array cannot be attached to the same IBM SCSI adapter with the SCSI device address jumper IDs required by the OASAS I software. o Connected to this IBM SCSI adapter is the disk array, which consists of three to seven IBM SCSI fixed disks. If there is not enough space in the PS/2 for all the hard drives an IBM PS/2 SCSI Storage Enclosure (#3510) or an IBM PS/2 External Storage Enclosure for SCSI Devices (#3511) containing the rest of the hard drives in the array will be needed. OASAS I Release 1.0 supports the following hardware: - IBM Personal System/2 386 System Units -- IBM Personal System/2 -- IBM Personal System/2 Model 55 SX (8555) -- IBM Personal System/2 Model 57 SX (8557) -- IBM Personal System/2 Model 70 386 (8570) -- IBM Personal System/2 model 70 386 (8570) Model A21 with the PS/2 486/25 Power Platform (TM) -- IBM Personal System/2 Model 80 386 (8580) -- IBM Personal System/2 Model 80 386 (8580) -- IBM Personal System/2 Model 90 XP 486 (8590) -- IBM Personal System/2 Model 95 XP 486 (8595) - IBM Personal System/55 386 System Units (Japan) -- IBM Personal System/55 Model 5550 SI/T1/V1 -- IBM Personal System/55 Model 5560 W -- IBM Personal System/55 Model 5570 T1/V1 -- IBM Personal System/55 Model 5580 Y - Fixed Disks -- IBM PS/2 160MB SCSI Fixed Disk Drive (for 8560, 8565, 8580, 8590, 8598, 3510 and 3511) -- IBM PS/2 320MB SCSI Fixed Disk Drive (for 8560, 8565, 8580, 8590, 8598, 3510 and 3511) -- IBM PS/2 400MB SCSI Fixed Disk Drive (for 8560, 8565, 8580, 8590, 8598, 3510 and 3511) - Other -- IBM 7546 Industrial Computer -- IBM PS/2 SCSI Storage Enclosure (#3510) -- IBM PS/2 External Storage Enclosure for SCSI Devices (#3511) -- PS/2 Micro Channel (R) SCSI Adapter (#1018) -- IBM PS/2 Micro Channel SCSI Adapter with Cache (#1005) (TM) Trademark of International Business Machines Corporation. (R) Registered trademark of International Business Machines Corporation. PROGRAMMING REQUIREMENTS: The systems programmer should acquire a license for and install IBM OS/2 SE 1.30.1 or later, the equivalent OS/2 SE 1.3 CSD level of 5015, or IBM OS/2 Version 2.0. ENVIRONMENT A typical application for OASAS I is a large data base or server environment. This environment most commonly uses a PS/2 Model 95 with at least the minimum hardware required to install IBM OS/2 SE 1.30.1 or later, the equivalent OS/2 SE 1.3 CSD level of 5015, or IBM OS/2 Version 2.0. In addition, for OASAS I there would be at least three IBM SCSI hard drives installed in the PS/2 Model 95 (space permitting), or in 3510s or 3511s using an additional SCSI adapter. For large single volume disk arrays, additional system memory may be required by file system programs such as the OS/2 HPFS CHKDSK and CACHE programs. INSTALLATION The OASAS I disk array comes with an installation procedure that ensures quick and easy installation of the disk array. SCSI HOST ADAPTER: The interface to the disk subsystem array is a SCSI adapter that resides in the host computer. The SCSI I/O address for this adapter is used during the OASAS I installation. FORMATTING THE DISK ARRAY: Supplied with the OASAS I disk array is a utility for formatting the disk array drives. For the format operation, all of the drives in the array must be of the same type and capacity. The disk array can appear as a large single logical volume or multiple volumes, depending on the user's preference. The array may be formatted as either FAT or HPFS. THE FAULT-TOLERANT DEVICE DRIVER: The OASAS I device driver consumes approximately 100KB of memory. While operating, it is completely transparent to the operating system. Then when the drives in the disk array appear as a single large volume (even with a failed disk drive), the disk array is recognized by OS/2 as a virtual SCSI disk drive. Continuous operation to the disk array is maintained during events, such as a single drive failure, reassignment of defective sectors, parity/Error Correction Code (ECC) block verification and the recreation of a replaced disk drive in the array. RELIABILITY OASAS I has an Error Recovery Procedure (ERP) for recovering data. FAILED DRIVE CORRECTION: OASAS I reconstructs the data that was on a failed disk drive, without having to bring down the system. CORRECTING FOR READ ERRORS: When a hard read error occurs, OASAS I automatically determines the correct data, presents it to the system and rewrites the data to the sector in which the read error occurred. CORRECTING FOR BAD SECTORS AND MEDIA DEFECTS: In this case, the ERP remaps the sector to a new sector. BACKGROUND RECREATION OF A DRIVE A replaced drive can be recreated as a background task. After replacing the drive, users can access the disk array while the drive is being recreated. If the drive that failed was contained in a 3510 SCSI enclosure, the system does not have to be brought down to replace it. This is also known as 'hot plugging' a drive. The recreation process takes approximately 20 seconds per megabyte of data on the replaced drive. If the process is being run as a background task, it will depend on how busy the processor is and how many other tasks are being run. The recreate utility always runs at the lowest task priority in the system. PERFORMANCE CONSIDERATIONS: The OASAS I Disk Array Management Software tolerates any single disk array drive failure with the implementation of RAID level 5 technology. Since the primary goal of RAID 5 is to provide data redundancy, most applications should run with about the same response time compared to a non-disk array configuration. However, in certain heavily-loaded environments with excessive writes, applications may run two to three times slower than a non-disk array configuration. This is favorable compared to a RAID 3 configuration such as 'data guarding,' which in extreme cases can degrade response time by a factor of up to 15 times. Note the implication here is that applications that are timing dependent and already tuned to an existing environment, may need to be reconfigured to reflect the increased response time of a disk array. With a failed drive in a six-drive RAID 5 array, the estimated overall performance degradation is about 30% compared to normal disk array operation. For applications environments where fault tolerance is not required, OASAS I has the option to disable fault-tolerant parity. Disabling parity on the disk array improves the performance for write-intensive applications. (A data striped disk array without fault tolerance is known as RAID 0.) The user has the option to enable fault tolerance on the disk array later. ADDITIONAL FEATURES REDUCED OVERHEAD: OASAS I can be used on arrays from three to seven SCSI fixed disk drives. The overhead for data protection is always the equivalent storage of one disk array drive. For example, 6 x 400MB drives would net the user approximately 2GB (gigabytes) of usable storage. This is minimal compared to the overhead for disk mirroring (or RAID 1) where the overhead is 50% of the real data storage. That is, 6 x 400MB drives would net the user approximately 1.2 gigabytes of usable storage. PLANNING INFORMATION CUSTOMER RESPONSIBILITIES: The customer is responsible for configuring the system with the necessary hardware to serve the application. The customer is also responsible for program setup and operation, implementation backup procedures and applicable problem determination procedures. The user should be familiar with the operation of the applicable IBM hardware and operating systems. PACKAGING: The OASAS I Release 1.0 product package contains the following: o OASAS I Program License Agreement o Diskette containing the OASAS I Release 1.0 machine-readable information and device drivers o OASAS I User Reference manual. SECURITY, AUDITABILITY AND CONTROL User management is responsible for evaluation, selection and implementation of security features, administrative procedures and appropriate controls in application systems and communication facilities. ORDERING INFORMATION Orders for new licenses will be accepted now. Unless a later date is specified, orders entered prior to October 22, 1991, will be assigned a schedule date of November 1, 1991. Shipment of orders will commence on the availability date. Orders entered after October 22, 1991, will be scheduled for shipment on the Friday following the week of order entry or as soon thereafter as supply permits. To order the program in this announcement, for order type specify the order type/program number, feature number, part number, program name, media and quantity. ORDER TYPE/ PROGRAM FEATURE PART NUMBER NUMBER NUMBER PROGRAM NAME MEDIA 5875-XXX 2089 92F1858 OASAS I 3.5-inch The available order type is as follows: o Program Package -- program diskette with documentation. TERMS AND CONDITIONS LICENSING: OASAS I is available from IBM as distributed by Integra Technologies, Inc. The terms and conditions of the supplier apply. They are included in the program package and are passed on to the customer. LIMITED WARRANTY: Not warranted by IBM. Warranty, if any, is as provided by the program supplier. Address any questions pertaining to warranty coverage to the program supplier. VOLUME DISCOUNT: Not applicable. NATIONAL EDUCATION LICENSE FEE: A National Education License Fee (NELF) is available under the terms and conditions of the Education Allowance Attachment. The NELF, which represents a 30% discount off the single unit price, is not subject to any further discount or allowance. PROBLEM DETERMINATION ASSISTANCE: Customer support will be available to assist the user in problem determination. IBM does not guarantee service results or represent or warrant that all errors or program defects will be corrected. CHARGES PROGRAM ONE-TIME NAME/NUMBER ORDER TYPE CHARGE OASAS I Release 1.0 92F1858 Program Package $ 795