The following is the text of an IBM Information Systems Group marketing brochure published in February 1985.


The IBM 3380 family of storage products meets the varied data storage requirements of today's large data processing systems. Advanced design and technology contribute to the excellent reliability. high performance and impressive environmental characteristics of the IBM 3380. It requires less electrical power, generates less heat, requires less floor space, and is priced less per megabyte when compared on an equal capacity basis with previous products.

Standard and Extended Capability models

IBM 3380s are identified as Standard or Extended Capability models. Extended Capability models have all the features of the Standard models and have Device Level Selection, a function designed to further improve availability and performance. Extended Capability models also can store or be upgraded to store 5.04 billion bytes (or gigabytes) in a single unit. Each IBM 3380 has four functionally independent actuators which access data stored on the two head and disk assemblies (HDAs) within each unit.

There are seven models of the IBM 3380 family: four 'A' models and three 'B' models. 'A' models (heads of string) contain additional logic to perform string controller functions. All models store data in count-key-data format with capacities of either 2.52 or 5.04 gigabytes of data, depending on the model.

IBM 3380 models available are:

Model Capacity controllers Device type
A04
2.52GB
1
standard
AA4
2.52GB
2
standard
B04
2.52GB
standard
AD4
2.52GB
2
extended capability
AE4
5.04GB
2
extended capability
BD4
2.52GB
extended capability
BE4
5.04GB
extended

Purchased Models AD4 and BD4 can be field-upgraded to the double-capacity AE4 and BE4 models, respectively. The A04 can be field-upgraded to an AA4. All models are attached to processor channels through storage directors on the IBM 3880 Storage Control. The 'A' models with two string controllers (the Dynamic Path Selection function) support connection to two separate storage directors, providing improved availability and performance. These models provide two paths for data flow between the IBM 3880 Storage Control and the individual actuators in the string. The internal paths for the Extended Capability models have been enhanced to allow simultaneous data transfer from any two actuators within the string, even within the same HDA. This function, Device Level Selection combined with Dynamic Path Selection, provides improved data availability and performance. In the MVS environment, the Dynamic Path Reconnect capability of the System/370 Extended Architecture operating system exploits these hardware functions to provide increased performance.

A string of Standard model 3380s can consist of a single 3380 Model A04 or AA4 and up to three 3380 Model B04 units. A string of Extended Capability 3380s can consist of one 3380 Model AD4 or AE4 and up to three 3380 Model BD4 and BE4 units, in any combination. Two strings of 3380s can be attached to each storage director of a 3880 Model 3 or cache storage control Model 23. An A04 string is not supported by the Model 23. Strings headed by an AA4, AD4 or AE4 must attach to two storage directors (usually on two separate 3880 Storage Controls). An AA4 string and an Extended Capability string can be attached to the same storage directors.

Model A04,
AA4, B04
AD4, BD4 AE4, BE4
General characteristics:
  HDAs per unit
2
2
2
  Actuators per HDA
2
2
2
  Actuators per unit
4
4
4
  Bytes per actuator
630MB
630MB
1,260MB
  Bytes per unit
2.52GB
2.52GB
5.04GB
  Bytes per full string
10.08GB
10.08GB
20.16GB
  Tracks per cylinder
15
15
15
  Cylinders per actuator
885
885
1,770
Performance:
  Average seek time
16ms
15ms
17ms
  Minimum seek time
3ms
3ms
3ms
  Maximum seek time
30ms
28ms
31ms
  Average latency
8.3ms
8.3ms
8.3ms
  Data transfer rate
3.0MB/s
3.0MB/s
3.0MB/s
Features:
  Dynamic Path Reconnect
  capability using XA
Yes¹
Yes
Yes
  Dynamic Path Selection
Yes¹
Yes
Yes
  Device Level Selection
No
Yes
Yes
  3880 Model 3
  or 23 attach
Yes²
Yes
Yes
  3880 Speed
  Matching Buffer
Yes
No
No
  Model intermix
  within string
B04 only
BD4 BE4
BD4, BE4
  Upgradable
A04 to AA4
AD4 to AE4³
BD4 to BE4
Not applicable

1. Except with AO4 models
2. The AO4 does not attach to 3880 Model 23
3. Purchased AD4 and BD4 units only via purchased field upgrades



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