IBM 2302 The
IBM 2302 is the
System/360 version of the
1302, with track formatting in accordance with S/360 DASD architecture rather than 7000 series architecture. It uses a non-removable module of 25 platters, of which 46 surfaces are used for recording. The 2302 Model 3 contains one module and the Model 4 two. There are two independent access mechanisms per module, one for the innermost 250 cylinders, and one for the outermost 250, tracks available to each access mechanism are called an
access group. The access mechanism provides one read/write head per track. Average rotational delay is 17 milliseconds (msec), and maximum is 34 msec. Maximum seek time per access group is 180 msec. The track size is 4985 bytes; with formatting information and alternate tracks, module capacity is stated as 112 MB. The 2302 attaches to IBM mainframes via a
IBM 2841 Storage Control Unit.
IBM 2305 The
IBM 2305 fixed head storage (a fixed-head disk drive sometimes incorrectly called a
drum) and associated IBM 2835 Storage Control were announced in 1970, The 2305 provides large-scale IBM computers with fast, continuous access to small-sized quantities of information. Its capacity and high data rate make it ideal for some systems residence functions, work files, job queues, indices and data sets that are used repeatedly.
IBM 2311 The
IBM 2311 Disk Storage Drive was introduced with the
2841 Control Unit in 1964 for use throughout the IBM
System/360; the combination was also available on the
IBM 1130 and the
IBM 1800. The drive also directly attaches to the
IBM System/360 Model 20 and the
IBM System/360 Model 25. All drives used the
IBM 1316 Disk Pack introduced with the IBM 1311. The 2311 Model 1 attaches to most IBM mainframes through a
2841 Control Unit; it attaches to the System/360 Model 25 thru a Disk Attachment Control which provides the function of the control unit. Disk packs are written in these attachments in IBM's
count key data variable record length format. The
2311 models 11 or 12 are used when attached to an integrated control of the System/360 Model 20 and the disk packs are written with a fixed sector format. The disk packs are not interchangeable between those written on the Model 1 and those written on the Models 11 or 12. The 2311 mechanism is largely identical to the 1311, but recording improvements allow higher data density. The 2311 stores 7.25
megabytes on a single removable IBM 1316 disk pack (the same type used on the IBM 1311) consisting of six platters that rotate as a single unit. The 2311 has ten individual read/write (R/W) heads mounted on a common actuator which moves in and out hydraulically and is mechanically detented at the desired track before reading or writing occurred. Each recording surface has 200 tracks plus three optional tracks which can be used as alternatives in case faulty tracks are discovered. Average seek time is 85 ms. Data transfer rate is 156
kB/s. Because the 2311 was to be used with a wide variety of computers within the 360 product line, its electrical interconnection was standardized. This created an opportunity for other manufacturers to sell
plug compatible disk drives for use with IBM computers and an entire industry was born.
IBM 2314/2319 s and empty covers on top of the drives.
IBM 2314 Disk Access Storage Facility Model 1 The
IBM 2314 Disk Access Storage Facility Model 1 was introduced on April 22, 1965, one year after the
System/360 introduction. It was used with the System/360 and the
System/370 lines. With the Two Channel Switch feature it could interface with two 360/370 channels. The 2314 Disk access mechanism was similar to the 2311, but further recording improvements allowed higher data density. The 2314 stored 29,176,000 characters (200×20×7294 bytes per track) on a single removable IBM 2316 disk pack which was similar in design to the 1316 but was taller as a result of increasing the number of disks from six to eleven. The 2316 disk pack containing the eleven diameter disks yielded 20 recording surfaces. The drive access consisted of 20 individual R/W heads mounted on a common actuator which was moved in and out hydraulically and mechanically detented at the desired track before reading or writing occurred. Each recording surface has 200 tracks. Access time was initially the same as the 2311, but later models were faster as a result of improvements made in the hydraulic actuator. Data transfer rate was doubled to 310 kB/s. The original Model 1 consists nine disk drives bundled together with one price; separately shipped was a storage control unit, a single drive module, and two four drive modules for a total of nine drives. The drives are mounted in individual drawers that are unlatched and pulled out to access the disk pack. Because of their appearance they acquired the nickname of "Pizza Ovens". Only eight drives of the nine are available to the computer at any one time. The ninth drive is there for a spare for the user and can also be worked on "offline" by a Field Engineer while the other drives are in use by the customer. Each drive's system address is determined in part by a user-swappable plug, one such plug denoting a spare drive not system accessible. This permits physically changing the address of a drive by changing the plug. A 2844 Control Unit can be added to the 2314 Control Unit which allows two S/360 Channels simultaneous access to two separate disk drives in the Storage Facility. Other 2314 models came later:
IBM 2314 direct access storage facility - A series In 1969 IBM unbundled the facility into separate models allowing up to nine drives (eight on line) attached to a
2314 Storage Control: •
2312 Disk Storage, a one drive module. •
2313 Disk Storage, a four drive module. •
2318 Disk Storage, a two drive module.
IBM 2319 • In a response to competition from
plug compatible manufacturers of 2314 equivalent storage subsystems, IBM beginning 1970 introduced a series of low priced three drive module 2319s which were manufactured by removing one module from the four drive module 2313, rebranding it as a 2319 A1 and offering it at a substantially reduced rental price. This had the effect of lowering the rental price to new customers while keeping the high rental price on existing customers. The 2319-A1 attaches to integrated controllers for only the System/370 Models 135 and 145. Conventional 2314 DASD such as the 2312 or 2318 can attach to the 2319-A1 • 2319 B series of three disk drives modules allow three, six or nine drive attachment to a new 2314 Model B Storage Control Unit.
IBM 3310 IBM introduced the
IBM 3310 Direct Access Storage Device on January 30, 1979, for
IBM 4331 midrange computers. Each drive had a capacity of 64.5 MB. The 3310 was a
fixed-block architecture device, used on
DOS/VSE and
VM, the only S/370 operating systems that supported FBA devices.
IBM 3330 The
IBM 3330 Direct Access Storage Facility, code-named
Merlin, was introduced in June 1970 for use with the IBM
System/370 and the IBM
System 360/195. The original announcement included the 3330 Model 1, with two drives, and the 3330 Model 2, with only one drive. The 3330 has removable disk packs, similar to its predecessors, and the packs hold 100 MB (404×19×13,030 bytes). Access time is 30 ms and data transfers at 806 kB/s. A major advance introduced with the 3330 is the use of
error correction, which makes the drives more reliable and reduces costs because small imperfections in the disk surface can be tolerated. The circuitry can correct error bursts up to 11 bits long through use of
fire codes. The initial configuration consists of one storage control unit (3830 Model 1) bolted to a 3330, with optionally three more 3330's bolted together. This is known as a string, making a maximum of eight drives in a string. In August 1972 IBM announced the
3830 Model 2 Storage Control and the
3333 Disk Storage and Control, separating the control unit from the string. The 3830 became a
director type of storage control, controlling one or more strings. The now first unit of the string, the 3333 contains a controller and two drives and it can control up to three attached 3330's for a maximum of eight drives in the string as shown in the illustration. The 3830 Model 2 can connect two 3333's for a maximum of 16 drives per storage control and the 3333 optionally has a string switch that enables it to be connected to two different storage controls. In 1973 IBM announced double density versions (-11 models) of the 3330 product line: the 3333–11, 3330-11 and the 3336–11; the 3336-11 Disk Packs hold up to 200 MB (808x19x13,030 bytes). It is not possible to mix single and double density drives within a string. It is possible to field upgrade existing 3330 Models to Model 11, but this is a major task, as the drives had to be converted, and all the existing data had to be copied to the new media. The 3330 was withdrawn in 1983.
IBM 3340 and 3344 The IBM 3340 and 3344 have similar characteristics. However, only a 3340 can serve as head of string; there are no A model 3344 drives, and a 3344 must be attached to a 3340 A model as head of string.
IBM 3340 The
IBM 3340 Direct Access Storage Facility, code-named
Winchester, was introduced in March 1973 for use with IBM
System/370. Three models were announced, the 3340-A2 with two drives and a controller, the models B2 (two drives) and B1 (one drive). B-units can connect to the model A2 to a maximum of eight drives. It uses removable data modules that included the head and arm assembly; an access door of the data module opens or closes during a mechanical load/unload process to connect the data module to the drive; unlike previous disk packs and cartridges there is no cover to remove during the insertion process. Access time is 25 millisecond and data transfers at 885 kB/s. Three versions of the removable IBM 3348 Data Module were sold, one with 35 megabyte capacity, another with 70 megabytes, the third also has 70 megabytes, of which 500 kilobytes were accessible with fixed heads for faster access. The 3340 also uses
error correction. It was withdrawn in 1984. The 3340 was developed in San Jose under the leadership of Ken Haughton. Early on, the design was focused on two removable 30 megabyte modules. Because of this 30/30 configuration, the code name
Winchester was selected after the famous
Winchester .30-30 rifle; subsequently the capacities were increased, but the code name stuck. One significant aspect of this product, and the reason that disk drives in general became known as "Winchester technology", was that this head design was very low cost and did not require the heads to be unloaded from the media. Winchester technology allowed the head to land and take off from the disk media as the disk spun up and down. This resulted in very significant savings and a large reduction of complexity of the head and arm actuating mechanism. This head design rapidly became a standard design within the disk drive manufacturing community. Up into the early 1990s the term
Winchester or
Winnie was used for hard disk drives in general long after the introduction of the 3340. A word derived from this name was used in the general sense of "hard drive" in several other languages for an even longer time, for example in
Russian (
винчестер, sometimes shortened to '
or '), but is gradually disappearing in most parts of the world.
IBM 3344 The IBM 3344 is similar to the 3340, except that it uses fixed media rather than removable 3348 data modules, each spindle has four logical drives each with the capacity of a 3348–70, there is no A (head of string) model and it is only available in dual drive models. The 3344-B2F is identical to the 3344-B2 except that both drives have fixed heads over some cylinders. Both 3344-B2 and 3344-B2F require a 3340-A2 or 3340-A2F as head of string. Inside, the 3344 is exactly the same as IBM 3350, the difference is only in the microcode in the control unit.
IBM 3350 The
IBM 3350 Direct Access Storage Facility, code-named
Madrid, was introduced in 1975 for use with
IBM System/370. Its non-removable head-disk assemblies (HDAs) are sealed and included the head and arm assembly. The 3350 disk geometry is 555 cylinders, 30 heads, and 19,069 bytes per track, which give each HDA a storage capacity of 317,498,850 bytes. Sealed HDAs were standard practice on all IBM DASD hereafter. Disk units are identified as Models A2, A2F, B2, B2F, C2, and C2F with each model containing two HDAs. Model A2 and A2F has one additional electronic board, allowing it to be connected to the control unit. They are referred to as controllers, and also sometimes head-of-string. The models are installed in strings of units with an A2 or A2F unit, and then up to three B2 units or up to two B2s and a C2. The A2 unit usually has a string switch, allowing it to be connected to two different storage control units. This allows two I/O operations simultaneously take place to two different HDAs in the string. The storage control unit can be a 3830 Model 2, or the ISC (Integrated Storage Control) found in the 3148, 3158 or 3168 cpu's. Also later control units (3880) are backwards compatible and can be used. The C2s unit also contains a controller, that can be connected to a storage control unit and serves as a secondary path to itself and the A2 and B2 units. The C2 controller is a spare, it can only be used when the controller in the A unit is broken, and subsequently powered off. It has also limited connections, usually the A unit has a string switch, but the C unit only can be connected to one storage control unit. The valid 3350 strings are: -A, -AB, -ABB, -ABBB, -AC-, -ABC-, or -ABBC- configurations. The "x2F", as in Model A2F, unit is a normal x2 unit, but its two HDAs also have a Fixed Head area over the first five cylinders, thereby reducing seek time to zero for these five cylinders. This fixed head area is intended to be allocated to the frequently accessed
HASP or
JES2 checkpoint area and thus greatly reduce head motion on the SPOOL device. The fixed head area can also be utilized for
TSO swap data (
MVT and
SVS) and system swap data (
MVS) wherein the swap data for SVS and MVS consist of blocks of pages that have been in memory when an
address space is selected for swap-out; those pages need not be contiguous and in general do not include pages that have not been modified since their last page-in. This system architecture greatly improves context switches between TSO users or batch regions. The IBM 3350 family was withdrawn in September 1994.
IBM 3370 and 3375 IBM 3370 IBM introduced the
IBM 3370 Direct Access Storage Device in January 1979 for
IBM 4331, 4341, and
System/38 midrange computers. It has seven fixed disks, and each unit has a capacity of 571 MB. It was the first HDD to use
thin-film head technology; research on that technology started at
Thomas J. Watson Research Center in the late 1960s. It uses film head technology and has a unit capacity of 2.52 gigabytes (two hard disk assemblies each with two independent actuators each accessing 630 MB within one 3380 unit) with a data transfer rate of 3 megabytes per second. Average access time was 16 ms. Purchase price at time of introduction ranged from $81,000 to $142,200. Due to
tribology problems encountered between heads and media, the first units did not ship until October 1981.
IBM 3390 The
IBM 3390 Direct Access Storage Device series was introduced November 1989, offering a maximum storage of up to 22 gigabytes in a string of multiple drives. Cost of a storage system varied by configuration and capacity, between $90,000 and $795,000. A 3390 string consists of an A unit placed in the middle, and optionally one or two B units bolted to its sides. The A unit can have four or eight devices, each B unit can have up to 12 devices. The 3390 is always running in four-path mode, connected to a 3990 storage control unit. Optionally the 3990 can have a second 3390 string attached, giving a maximum of 64 devices in the subsystem. Packaged in Hard Disk Assemblies with two actuator-head units and one set of platters, a model 1 HDA provides 1.89 GB before formatting and a model 2 provides 3.78 GB/HDA. The Model 3 enhancement to the drive family, announced September 11, 1991, increased capacity 1.5 times to 5.67 GB/HDA and the Model 9, announced May 20, 1993, further increased capacity 3 times to 11.3 GB/HDA. All the preceding DASD models are equipped with a large AC motor, driving the HDA with a belt; however, the 3390 HDA is directly driven by a DC motor that is included in the enclosure. The 3390 Model 9 was the last Single Large Expensive Disk (sometimes called SLEDs) drive announced by IBM.
IBM 9340 and 9345 IBM 9345 The
IBM 9345 HDD first shipped in Nov 1990 as an
RPQ on IBMs SCSE (SuperComputing Systems Extensions). Developed at IBM's
San Jose, California laboratory under the code name Sawmill. It was an up to 1.5 GB full height 5-inch HDD using up to 8 130 mm disks. It was the first HDD to use MR
(Magneto Resistive) heads.
IBM 9340 In October 1991 the 9345 DASD was announced as part of the IBM 9340 channel-attached, count key data (CKD) DASD subsystem family which attached to IBM mainframes including the ES/9000 processor family. The 9345 DASD Model 1 had two 1.0 GB HDDs while the Model 2 had two 1.5 GB HDDs. For most practical applications, the 9340/9345 was functionally equivalent to a 3990/3390, although without non-volatile RAM cache of the 3990 and with a somewhat shorter maximum block length than the 3390. The OS's
IOS component learned of this device's characteristics through a special initializer, IECCINIT, which also serviced other DASD device types, and for the same purpose. It was at initialization-time that the OS learned that the 9340 has no non-volatile cache and the 9345 has a shorter than expected track capacity. The initializer, therefore, assigned a different device type than the 3990/3390.
9330 family of disk drives • 9331 Diskette Unit models 1 and 11 contained one 8-inch FDD while the models 2 and 12 contained one 5-inch FDD. • 9332 Direct Access Storage Device used the IBM 0667 HDD. • 9333 High Performance Disk Drive Subsystem used the IBM 0664 or IBM 0681 HDDs depending upon subsystem model • 9334 Disk Expansion Unit attaches from one to four SCSI HDDs to the RS/6000 system. • 9335 Direct Access Storage Subsystem This HDD used in this subsystem was developed under the code name "Kestrel" at IBM Hursley, UK, and was an 850 MB HDD using three 14-inch disks with dual
rotary actuators, each actuator accessing three surfaces with two heads per surface. There is no known OEM version of this HDD. • 9336 Disk Unit used the IBM 0681 HDD (Redwing) • 9337 Disk Array Subsystem used the IBM 0662 (Spitfire) or 0663 (Corsair) HDDs. ==HDDs offered for IBM small systems==