Cached controllers added for the new 9340 disk subsystem
The new 9340 disk subsystem family has been extended to include three new cached models of the 9343 Storage Controller. The CC2, CC4 and DC4 respond directly to the market-driven requests for 9340 cache function, with performance said to exceed the native performance of the 9343/9345 subsystem. The cache logic in the 9343 operates transparently to the host system and is claimed to be fully compatible with the uncached models. For MVS/ESA, a partitioned data set search assist is now available for parallel channels, offering improved performance on directory searches, with optimal partitioned data set search performance on the new cached models, IBM claims. An Escon distance extension enables the 9343 Escon models to be attached to a host up to 26.7 distant for remote on-line data archiving capability. The Licensed Internal Code that provides the Escon distance extension and search assist will be provided to at no additional charge. IBM says that preliminary performance runs with a cached 9340 subsystem using a laboratory stress input-output driver workload show response time improvements of up to 40% when compared to an uncached 9340 running the same stress input-output driver workload. In an MVS/ESA environment, partitioned data set performance improvements can be obtained from the search assist provided for the 9340 family on parallel channels. The ability to extend the installation distance between a host system to 26.7 miles using the Escon distance extension in conjunction with Extended Distance Facility channels enhances configuration flexibility of the subsystem (No! Surely not!). However, the Escon distance extension is applicable only to the 9343 Models D04 and DC4 and the 9034 Escon Converter Model 1 is not supported for extended distance configurations. To achieve the maximum 26.7 mile distance, two Escon Directors and an Extended Distance Facility host are required. The 9343 Models CC2, CC4 and DC4 maintain copies of frequently accessed data files in high-speed semiconductor memory. The elimination of mechanical seek time and latency delays for read input-output operations improves response time and increases subsystem throughput. IBM says that three distinct characteristics separate the 9340 family from other count-key-data storage products – entry price, capacity options – users can upgrade in 2Gb or 3Gb increments – and physical operating environment.
Lowest entry price
With the new cache models, the 9340 offers IBM’s lowest entry price for an uncached or cached count-key-data subsystem. The 9343 CC2 Storage Controller with single storage cluster controller and 32Mb cache, two parallel channels, two device paths and support for up to eight 9345 modules costs $57,200 or $3,075 per month. The 9343 DC4 Storage Controller with dual storage cluster controllers and 64Mb cache, four Escon channels, four device paths and support for up to eight 9345 modules comes in at $92,400 and rental is $4,975 per month. The feature to support up to 16 9345 modules costs $4,000 or $205 each month in rental fees. 9343 models CC2, CC4 and DC4 are planned to ship sometime in the fourth quarter this year, and partitioned data set search assist are to be available from June 1.
3990 Storage Control Model 3 Enhancements
Enhancements to the 3990 Storage Controller include functional improvements to the Licensed Internal Code along with new DFSMS/MVS 1.1 capabilities. The enhancements are to Fast Dual Copy, a nonsynchronous operations enhancement for Escon environments, a partitioned data set search assist for MVS/ESA users, the Extended Platform feature, and a 3990 Escon distance extension, available for both both the Model 2 and the Model 3. However the Concurrent Copy feature, while welcome, cannot be implemented from DB2, so it is not yet system managed and unlikely to be available before the second quarter of next year. DFSMS is a prerequisite for most of the new features. Concurrent Copy, a new 3990 Model 3 extended function, provides point-in-time data set copies w
hile maintaining concurrent read-write access to the data sets being copied. Except for a brief period for initialisation of Concurrent Copy, in most cases it will no longer be necessary to stop applications in order to back up data. This shrinks the batch back-up-window requirements and increases availability. Both DFSMS-managed and non-DFSMS-managed data sets are supported by Concurrent Copy. The Extended Platform features, 6203 and 6204, provide the same hardware as the pre-Escon and Escon Platform Enabler features, 6201 and 6202, but they can be ordered without the Escon adaptor. It is a prerequisite for installing Escon adaptor features and for existing and future enhancements to the 3990 Models 2 and 3. DFSMS/MVS is needed for 3990 Model 3 Licensed Internal Code for the concurrent copy extended function, enhanced dynamic cache management, and sequential data striping. DFSMS/MVS, in addition to new functions, is an integration of previously available management functions. IBM says that this enables easier installation, simplified maintenance, reduced testing and a higher quality of code. The software – DFP for active data; DSS for moving data; HSM for inactive data; and RMM for tape management – comes in a single package, and once data is designated, users have to trust DSFMS to decide where best to place it in the storage hierarchy.
Pay only for usage
Users get the whole bundle but pay only for usage. There are improvements to dynamic cache management for DFSMS-managed data, as well as sequential data striping. Enhanced dynamic cache management on the 3990-3 with DFSMS/MVS offers improved performance in some environments by more effectively managing use of cache. IBM says that previously untuned 3990 cache subsystems using the enhanced dynamic cache management function can achieve performance that approaches the best levels achieved by manually tuning – people still do it better. With enhanced dynamic cache management, cache management and tuning actions are implemented dynamically, using data gathered on a continuous basis from the storage control and channel subsystem. This takes cache and data set activity variations into account and acts upon them as changes occur. It uses techniques that automatically and dynamically identify efficient cache candidates and optimise use of cache where it is overcommitted. Sequential data striping for DFSMS-managed sequential data sets exploits the increased data rate and single or multiple 3990-3s. It enables requests to process concurrently on multiple volumes and ships June 26.
