Barracuda 18LP Family: ST39175LW/LC ST318275LW ... - Seagate

Barracuda 18LP Product Manual, Rev. E 5
3.0 General description
Barracuda 18LP drives combine magnetoresistive (MR) heads, partial response/maximum likelihood (PRML)
read channel electronics, embedded servo technology, and a SCSI-3 (Fast-20 and Fast-40) interface to provide
high performance, high capacity data storage for a variety of systems including engineering workstations, network
servers, mainframes, and supercomputers.
Fast-20 and Fast-40 (also known as Ultra-1 SCSI and Ultra-2 SCSI, respectively) are negotiated transfer rates.
These transfer rates will occur only if your host adapter also supports these data transfer rates. This drive also
operates at SCSI-1 and SCSI-2 data transfer rates for backward compatibility with non-Fast-20/Fast-40 capable
SCSI host adapters.
Table 1 lists the features that differentiate the various Barracuda 18LP models.
Table 1:
Drive model number vs. differentiating features
Model number
Number
of heads I/O circuit type [1]
Number of I/O
connector pins
Number of I/O
data bus bits
ST39175LW 5 multimode (SE/LVD) 68 16
ST39175LC 5 multimode (SE/LVD) 80 16
ST318275LW 10 multimode (SE/LVD) 68 16
ST318275LC 10 multimode (SE/LVD) 80 16
[1] See Section 9.6 for details and definitions.
The drive records and recovers data on 3.5-inch (86 mm) non-removeable discs.
The drive supports the Small Computer System Interface (SCSI) as described in the ANSI SCSI-2/SCSI-3
SPI-2 interface specifications to the extent described in this manual (volume 1), which defines the product performance
characteristics of the Barracuda 18LP family of drives, and the SCSI Interface Product Manual (volume
2), part number 77738479, which describes the general interface characteristics of this and other families
of Seagate SCSI drives.
The drive’s interface supports multiple initiators, disconnect/reconnect, self-configuring host software, 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 nonreplaceable
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 disassemble
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.
Barracuda 18LP drives use a dedicated landing zone at the innermost radius of the media to eliminate the possibility
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 during
shipping and handling. The shipping lock automatically disengages when power is applied to the drive and
the head load process begins.
Barracuda 18LP drives decode track 0 location data from the servo data embedded on each surface to eliminate
mechanical transducer adjustments and related reliability concerns.
A high-performance actuator assembly with a low-inertia, balanced, patented, straight-arm design provides
excellent performance with minimal power dissipation.