FASTRAND was a magnetic drum mass storage system built by Sperry Rand Corporation for their UNIVAC 1100 series

UNIVAC 1100/2200 series

The UNIVAC 1100/2200 series is a series of compatible 36-bit computer systems, beginning with the UNIVAC 1107 in 1962, initially made by Sperry Rand...

 and 490/494 series computers.

A voice coil actuator moved a bar containing multiple single track recording heads, so these drums operated much like moving head disk drives with multiple disks. The heads "flew" on self acting hydrodynamic air bearings. The drums had a plated magnetic recording film.

The Fastrands were very heavy (5,000 pounds) and large, approximately 6' long. They required special rigging and mounts to install. At the time of their introduction the storage capacity exceeded any other random access mass storage disk or drum.
There were three models of FASTRAND drives:

• FASTRAND I had a single drum. The large mass of the rotating drum caused gyroscopic
  Gyroscope
  A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...
  
   activity in the unit, making it tend to spin on the computer room floor as the Earth rotated under it. Very few of these devices were delivered.
• FASTRAND II (the majority of units produced) had two counter-rotating drums to eliminate the gyroscopic instability. One actuator bar with heads was located between the drums.
• FASTRAND III, introduced in 1970, was physically identical to the FASTRAND II, but increased the recording density by 50%.

Specifications (FASTRAND II)

Storage capacity: 22,020,096 36-bit words = 132,120,576 6-bit FIELDATA characters = 99 megabytes (8-bit bytes) per device

Drum rotation rate: 880 RPM (14.7 rotations per second)

Heads

Disk read-and-write head

Disk read/write heads are the small parts of a disk drive, that move above the disk platter and transform platter's magnetic field into electrical current or vice versa – transform electrical current into magnetic field...

: 64

Sector

Disk read-and-write head

Disk read/write heads are the small parts of a disk drive, that move above the disk platter and transform platter's magnetic field into electrical current or vice versa – transform electrical current into magnetic field...

 size: 28 36-bit words

Track size: 64 sectors (1,792 36-bit words)

Track density: 105 tracks per inch

Average Access time (seek time plus rotational latency): 92 milliseconds

Data transfer rate: 26,283 36-bit words per second = 118 kilobytes per second (8-bit bytes) on 1100 series machines

Recording density

Computer storage density

Memory storage density is a measure of the quantity of information bits that can be stored on a given length of track, area of surface, or in a given volume of a computer storage medium. Generally, higher density is more desirable, for it allows greater volumes of data to be stored in the same...

, one-dimensional: 1,000 bits per inch (along one track)

Recording density, two-dimensional: 105,000 bits per square inch of drum surface

Max FASTRAND devices (drum units) per controller: 8

Controller

Disk controller

The disk controller is the circuit which enables the CPU to communicate with a hard disk, floppy disk or other kind of disk drive.Early disk controllers were identified by their storage methods and data encoding. They were typically implemented on a separate controller card...

price: $41,680 (1968 dollars)

FASTRAND device price: $134,400 (1968 dollars)

Weight per FASTRAND device: 4,500 pounds

Weight per kilobyte: 6 ounces (170.1 g)

Storage allocation

Despite the name, FASTRAND was slow. The head positioning time was significant, so software allocated storage by tracks (1,792 words, 10,752 characters or 8,064 8 bit bytes) or "positions", a group of 64 tracks (114,688 words, 688,128 characters or 510,096 8 bit bytes) which were under the heads at a single time. This storage allocation method remained on the 1100 series machines long after drums had been replaced by disks.