History (1991): Magnetic and Optical Discs by IBM

IBM Corp. (Rochester, NY) announced no less than one hundred new hardware or software products especially for its mainframe computers.

Peripherals didn’t account for the smallest part of the announcement with high and middle-end drives, optical WORM and rewritable disk libraries, and a RAID disk unit.

Capacity of 3390 drives increase by 50%· The 10.8-inch high 3390 HDD series included model 1 and 2 drives to which have been added model 3. The main enhancement is the number of tracks per platter on account of a new thin-film media: 1,113 for model 1, 2,226 for model 2, 3,339 for model 3.

This leads to the long-awaited model 3 with a 5.676GB capacity per HDA, 50% more than in model 2 for the same size.

The leading specs of these units are mainly the same except for one of them, and not the least important, the head is slower. Average access time was 9.5ms for model 1, 12.5 ms for model 2 and is now 15ms for the latest model 3. This could keep back possible users that work on intensive transaction processing applications.

Additionally, the 3990 control unit can support approximately 180GB for $117,490 without cache and $213,690 with a 32MB cache with 3390 Model 3. It will cost a little over $10 to store 1MB with a configuration reaching a total 91GB capacity, by associating a 22GB A38 model ($251,350) and two complementary B3C models, each one with a 34GB capacity and costing $337,900. The price per megabyte comes to closely 20% less than with a configuration based on the previous 3390 model 2. These new model 3 drives can be connected to Escon’s optical fiber network and will permit to place the drives in another area than where the mainframes are.

This announcement proves that IBM intends to keep the lead in storage peripherals for mainframes that represent an important profit for the company that holds 80% of the worldwide market.

Compatible manufacturers are having more and more trouble following IBM’s technological advance. Amdahl Corp. (Sunnyvale, CA) is far away with its DASDs from Fujitsu. Hitachi Data Systems (Santa Clara, CA) announced shortly after its 7390 model 3 drives, shipping in 2092, with an equal capacity based on 9.5-inch platters and a faster average access time, 12.5ms.

This time for its mid-range computers (4281, low-end ES19000), IBM has launched its 9340 subsystems with smaller capacities but faster access times (10 or 11ms) and a transfer rate still a bit higher at 4MB/s. The 9340 can hold 2 to 486GB depending on the configuration.

A disk array for scientific computers
The RAID-3 type 9570 Disk Array Subsystem is mainly targeted by Big Blue for its technical and scientific applications. It includes 8 to 64 disks, with a maximum capacity of 146, 167 or 183GB depending on the size of the blocks used, 16,32 and 64KB respectively.

The 9570 can move data at a maximum rate of 55MB/s with an HPPI interface (High Performance Parallel Interface).

Optical WORM and erasable disk jukeboxes
Here IBM has taken the jukeboxes shown at the AIIM last April in Washington DC to add new configurations. The same libraries of 32 or 144 5.25-inch optical disks are bought from Hewlett-Packard. The same 3995 reference includes this time additional units that can use optical 625 to 650MB disks, not only WORM type but also magneto-optical erasable type, but not both at the same time.

The new units are slated to ship in late 1992. It’s the first time that the company puts in its catalog 5.25-inch erasable optical disks. The origin of the drives and the media is not known but are most probably bought from OEMs like Mitsubishi and Sony.

IBM 3995 Optical Library Dataservers

This article is an abstract of news published on the former paper version of Computer Data Storage Newsletter on issue ≠45, published on October 1991.