IBM System/370 145 Manual page 106

Table 20.10.1 compares the capacity and timing characteristics of the
3330-series with those of the 2314 and the 2321 Data Cell Drive. The
increase in capacity achieved by replacing a 2314 or a 2321 with a 3330-
series string depends upon the block size chosen for the data on the
3330. For example. if the 2314 full-track block size of 7294 bytes is
maintained for a given data set on the 3330 to avoid programming
changes, the 3330 yields a 91~ increase in full pack capacity (almost
twice the capacity). However, reblocking to a full track on the 3330,
13,030 bytes, yields a 242~ full pack capacity increase. If not enough
processor storage is available to alloca.te I/O areas of 13,030 bytes,
lowering the 3330 block size to one-half of a 3330 track yields a 239%
increase in full pack capacity.
If a 2321 is replaced by a 3330-series string, six full-track blocks
of data from the 2321 (2000 bytes/2321 track) can be placed on each 3330
track, if full-track blocking is used, for a total of 92,112,000 bytes
per 3336 pack (12,000 bytes times 7676 tracks per 3336 Modell). Thus,
slightly over four 3336 Model 1 packs provide the capacity equivalent of
ten data cells, or a full 2321 drive, if full tracks are used. Ten full
data cells, blocked full track, also can be contained in slightly more
than four 3336 packs if half-track blocking is used on the 3336 Modell.
self-formatting records are written on 3336 packs the same as on 2316
packs. However, each physical area written (count, key, and data) has a
field of error correction code appended to it for data validity checking
by the 3830 or integrated storage control instead of the cyclic check
area used on the 2314. The correction code used detects single burst
errors of 22 bits or less and corrects single burst errors of 11 bits or
less.
Table 20.10.1. capacity and timing characteristics of 3330-series and
2314 disk storage and the 2321 Data Cell Drive
Characteristic 3330-series 2314 2321
capacity in bytes truncated
to the nearest thousand
(full-track records)
Pack or cell
100,018,000 29,176,000 39,200,000
String or Data Cell Drive
2 drives/cells 200,036,000 58,352,000 78,400,000
4 drives/cells 400,073,000 116,704,000 156,800,000
6 drives/cells 600,109,000 175,056,000 235,200,000
8 drives/cells 800,146,000 233,408,000 313,600,000
10 cells
- -
392,000,000
Access time (ms)
Maximum
55
130 600 (for strip
select and load)
Average 30 60
175 (minimum
for strip select
and load)
Average cylinder-to- 10 25
95 (on a strip)
cylinder
Time channel busy
searching when SET
SECTOR is used (ms)
Minimum .120
- -
Maximum .380
-
-
Rotation time (ms)
16.7 25
50 (strip on drum)
Rotation speed (rpm) 3600 2400 1200
Data transfer rate
(KB)
806 312 55
96 A Guide to the IBM System/370 Model 145