Storagetek 9710 User Manual download pdf (Page 53)

MR0012J 9710 System Assurance Guide 4-13

SCSI Cabling

Cable Length Subtraction

When considering the length of an external SCSI interface bus, you must

subtract the length of bus already inside the 9710 from the maximum allowed

cable length. The individual cable measurements inside the 9710 are:

• From I/O tower to drive: 1.2 m (4 ft)

• Daisy chains between drives: 0.5 m (18 in.) each

• From I/O tower to library control: 2.4 m (8 ft)

• From drive to library control (library control can be daisy chained from the

drive data bus):

- 0.5 m (18 in.), or

- 1.2 m (4 ft), or

-1.8 m (6 ft)

The total length of cable that must be subtracted from each bus is shown in

Table 4-4. For the IBM AS/400 system, always subtract 1.2 m (4 ft) from the

control or data bus. The AS/400 does not allow daisy chains.

Table 4-4. SCSI Cable Length Subtraction

Number of drives on

the same data bus

Are data and control on

the same bus? (Yes/No)

Subtract this value from

maximum allowed cable length

1 (always 1 for AS/400) no (always no for AS/400) 1.2 m (4.0 ft) from drive bus