Seagate Cheetah 18XL, Руководство по эксплуатации продукта

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Cheetah 18XL Product Manual, Rev. A 5
3.0 General description
Cheetah 18XL drives combine giant magnetoresistive (GMR) heads, partial response/maximum likelihood
(PRML) read channel electronics, embedded servo technology, and a wide Ultra160 SCSI interface to provide
high performance, high capacity data storage for a variety of systems including engineering workstations, net-
work servers, mainframes, and supercomputers.
Ultra160 SCSI uses negotiated transfer rates. These transfer rates will occur only if your host adapter supports
these data transfer rates and is compatible with the required hardware requirements of the I/O circuit type. This
drive also operates at Ultra160 data transfer rates.
Table 1 lists the features that differentiate the two Cheetah 18XL models.
Table 1: Drive model number vs. differentiating features
[1] See Section 9.6 for details and definitions.
The drive records and recovers data on approximately 3.3-inch (84 mm) non-removeable discs.
The drive supports the Small Computer System Interface (SCSI) as described in the ANSI SCSI interface
specifications to the extent described in this manual (Volume 1), which defines the product performance char-
acteristics of the Cheetah 18XL family of drives, and the SCSI Interface Product Manual, part number
75789509, which describes the general interface characteristics of this and other families of Seagate SCSI
drives.
The drive’s interface supports multiple initiators, disconnect/reconnect, and automatic features that relieve the
host from the necessity of knowing the physical characteristics of the targets (logical block addressing is used).
The head and disc assembly (HDA) is sealed at the factory. Air circulates within the HDA through a non-
replaceable filter to maintain a contamination-free HDA environment.
Refer to Figure 2 for an exploded view of the drive. This exploded view is for information only—never disassem-
ble the HDA and do not attempt to service items in the sealed enclosure (heads, media, actuator, etc.) as this
requires special facilities. The drive contains no replaceable parts. Opening the HDA voids your warranty.
Cheetah 18XL drives use a dedicated landing zone at the innermost radius of the media to eliminate the possi-
bility of destroying or degrading data by landing in the data zone. The drive automatically goes to the landing
zone when power is removed.
An automatic shipping lock prevents potential damage to the heads and discs that results from movement dur-
ing shipping and handling. The shipping lock automatically disengages when power is applied to the drive and
the head load process begins.
Cheetah 18XL drives decode track 0 location data from the servo data embedded on each surface to eliminate
mechanical transducer adjustments and related reliability concerns.
Model number
Number
of active
heads
I/O circuit type [1]
Number of I/O
connector pins Number of I/O
data bus bits Data buffer
size (MB)
ST318404LW 6 Single-ended (SE) and low
voltage differential (LVD) 68 16 4
ST318404LC 6 Single-ended (SE) and low
voltage differential (LVD) 80 16 4
ST39204LW 3 Single-ended (SE) and low
voltage differential (LVD) 68 16 4
ST39204LC 3 Single-ended (SE) and low
voltage differential (LVD) 80 16 4