Seagate STT20000N, Руководство по эксплуатации продукта

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Introduction Chapter 1
STT20000N Product Manual Page 5
Typical system configurations
The SCSI standard supports up to eight SCSI addresses or IDs. These IDs refer to
host adapters or peripheral devices such as printers, magnetic disks, or tape drives.
The eight devices or hosts are daisy chained together. Figure 1-3 shows sample
configurations of SCSI systems.
Figure 1-3
SCSI system—sample configurations
COMPUTER
SYSTEM
HOST
ADAPTER
SINGLE INITIATOR - SINGLE TARGET
COMPUTER
SYSTEM
HOST
ADAPTER
SINGLE INITIATOR - MULTIPLE TARGET
COMPUTER
SYSTEM
HOST
ADAPTER
MULTIPLE INITIATOR - MULTIPLE TARGET
COMPUTER
SYSTEM
HOST
ADAPTER
SCSI
TAPE
DRIVE
SCSI
TAPE
DRIVE SCSI
TAPE
DRIVE
MAGNETIC
DISC,
PRINTER, or
OPTICAL
DISK
MAGNETIC
DISC,
PRINTER, or
OPTICAL
DISK
MAGNETIC
DISC,
PRINTER, or
OPTICAL
DISK
MAGNETIC
DISC,
PRINTER, or
OPTICAL
DISK
SCSI BUS
SCSI BUS
SCSI BUS
Minicartridge technology overview
Having evolved from the original mass-storage medium—reel-to-reel, 1/2-inch tape
storage- the minicartridge technology of today offers fast, efficient, high-capacity
storage in a compact, easy-removable hard-shell package. In little more than a
decade, storage capacities have increased from some 60 megabytes (Mbyte) on 9
tracks (QIC-24, 1982) to the 20-Gbyte capacity achievable with the STT20000 SCSI
minicartridge drive on a single Travan TR-5 cartridge.
The streaming-tape intelligence in this minicartridge drive provides a continuous
tape motion with an uninterrupted, precisely coordinated flow of data to and from the
minicartridge. This "streaming" motion combined with the "serpentine" recording
method is one element that contributes to the increased storage capacities,
efficiency, and speed of today's minicartridge technology.
Use of the "serpentine" recording method exploits the bi-directional capabilities of
the cartridge. With this method, the tape is not rewound at the end of a track.
Instead, the write-read heads are logically or mechanically switched to a different
position on the tape and another track is written or read in the reverse direction.
That is, the drive first records track 1 in one direction and when the end of the tape
is reached, the head is moved and the direction of tape motion is reversed to record
a second track This serpentine process continues until the entire tape is recorded.
The individual tracks are sequential to minimize the amount of head motion as the
heads change position for each track.