Seagate ST3300655LW manual Interface transfer rates supported, Scsi interface cable requirements

Table 16 shows the interface transfer rates supported by the various drive models defined in this manual.

Table 16: Interface transfer rates supported

		Maximum transfer rate
Interface type/
		Asynchronous			Fast-20	Fast-40	Fast-80	Fast-160
drive models			Fast-5	Fast-10	(Ultra)	(Ultra2)	(Ultra160)	(Ultra320)
SE	ST3300655LW/LC
	ST3146855LW/LC	yes	yes	yes	yes	no	no	no
	ST373455LW/LC
LVD	ST3300655LW/LC
	ST3146855LW/LC	yes	yes	yes	yes	yes	yes	yes
	ST373455LW/LC

10.6.3SCSI interface cable requirements

The characteristics of cables used to connect parallel interface drives are discussed in the ANSI standards ref- erenced in this section.

10.6.3.1Cable requirements

The characteristics of cables used to connect Ultra320 SCSI parallel interface devices are discussed in detail in Section 6 of ANSI Standard T10/1365D Rev. 3. The cable characteristics that must be considered when interconnecting the drives described in this manual in a Ultra320 SCSI parallel, daisy-chain interconnected system are:

•characteristic impedance (see T10/1365D Sections 6.3.3 and 6.3.4)

•propagation delay (see T10/1365D Sections 6.3.6 and 6.3.7)

•stub length (see T10/1365D Section 6.9)

•device spacing (see T10/1365D Section 6.9)

To minimize discontinuances and signal reflections, cables of different impedances should not be used in the same bus. Implementations may require trade-offs in shielding effectiveness, cable length, number of loads and spacing, transfer rates, and cost to achieve satisfactory system operation. If shielded and unshielded cables are mixed within the same SCSI bus, the effect of impedance mismatch must be carefully considered. Proper impedance matching is especially important in order to maintain adequate margin at FAST-20, FAST- 40, FAST-80, and FAST-160 SCSI transfer rates.

Note. For LVD operation, twisted pair cables are recommended. For LVD Fast-40 operation, twisted pair cables are strongly recommended. For Fast-80 and Fast-160 operation, twisted pair cables are required.

LC Models

The 80-pin connector option provided on LC models is intended for use on drives that plug directly into back- plane connector in the host equipment. In such installations, all backplane wiring segments are subject to the electromagnetic concepts presented in Standard T10/1365D, Rev. 3, Section 6. For LC model drives, installa- tions with connectors on cables are not recommended.

10.6.4Mating connectors

Part numbers for the different type connectors that mate with the various Cheetah 15K.5 SCSI I/O connectors are given in the sections following.

Cheetah 15K.5 SCSI Product Manual, Rev. J 59