Fujitsu started shipping the F6427 magnetic disk unit in November 1992. It combined large storage capacity — up to 45 GB per unit — with high performance — an average positioning time of 12 milliseconds and an average rotational latency of 6.9 milliseconds.
Eight-inch hard disk drives were used to give up to six times the recording capacity in the same installation space as the previous F6425H model. Complete systems could be constructed by connecting the F6427 to a F1700 file control unit.*1
*1. The F1700 file control unit boosted the operational efficiency of the F6427. Fujitsu offered two types of file control units: the F1700B for large systems and the F1700S for small systems.
The F6427 array disk unit*2 had the following characteristics:
- Four-path cross-call function: enabled simultaneous read/write operations to any four drives in the same string (disk group) for high throughput and high reliability.
- Live expansion: able to add units to an existing string, add new strings, or add drives to a unit (one four-drive enclosure at a time) without interrupting user operations at the installation location.
- Database assistance mechanism: offloaded database (RDB II) query and statistical processing, normally done by the host computer, to the subsystem. These operations were done by a dedicated database processor in the magnetic disk controller. This mechanism reduced loading on the host computer’s CPU, reduced traffic on the communications channel, and shortened I/O execution times.
*2. The term “array disk” was used at the time, but eventually “disk array” would become the standard term.
|Initial shipping date||November 1992|
|Storage capacities||Per unit||KA1/KB1 : 11.34GB
KA2/KB2 : 22.68GB
KA3/KB3 : 34.02GB
KA4/KB4 : 45.36GB
|HA1/HB1 : 7.56GB
HA2/HB2 : 15.12GB
HA3/HB3 : 22.68GB
HA4/HB4 : 30.24GB
|Drive enclosure||2,835 MB||1,890 MB|
|Track capacity||47,476 byte|
|Data transfer speed||4.5 MB/s|
|Average positioning time||12 ms|
|Average rotational latency||6.9 ms|
|Data format||CKD variable|
|Field upgrades||In increments of four-drive enclosures|
|Data transfer speed||Specifications of the F1700 file control unit||3.0 MB/s，4.5 MB/s|
|Optical channels||6.0 MB/s，9.0 MB/s|
|Number of channels||4 or 8||8，16，24, or 32|
|Number of simultaneously active channels||2 or 4||4，8，12, or 16|