HP Integrity NonStop H-Series - Manual (Page 27)

Chapter Five - SCSI Bridge Electronics
Tandem 5142-xSE Rackmount Tape Subsystems User Guide 1 7
5.1 Introduction to the Subsystem Display
At the heart of the display system is the Infourmm fast SCSI bridge, which provides performance
information about the tape operation. In addition to bridging communications between the host and
tape drive, Infourmm autonomously sends commands to the tape drive to extract the data necessary for
the display. A high-performance CPU and dual SCSI buses allow the unit (1) to appear to the host as a
tape device on the host bus, and (2) to interface with the tape drive as a new host on the tape bus. This
private tape bus can operate independently of a host to provide such capabilities as tape mirroring, off-
line drive testing and tape duplication. Other features include: Fast SCSI-2 design, software configuration
retained in nonvolatile memory, flash memory for firmware upgrade, and low semiconductor parts
count for reliability.
5.2 Front Panel LCD
A four-line, eight-character-per-line, backlit LCD provides you with performance information,
configuration selections, diagnostic and special utility menus. During tape activity, the LCD shows the
current tape-drive operation, a bar graph tracking tape capacity, and items such as total data
transferred, average transfer rate, compression ratio, ECC rate percentage, remaining tape capacity, and
rewrite percentage. When you enter the configuration, diagnostic or utility menus, the LCD presents a
series of items to choose from and instructions to follow.
Mode
Switch
4-Line LCD,
8-Characters per line
Programmable
Error-Alert LED
Compression
Indicator LED
Figure 13 Display unit controls and indicators
5.3 Mode Switch
The mode switch is located in the right, lower corner of the display unit. It is used to select the SCSI ID,
access the off-line utilities and to perform the initial setup of the subsystem.
5.4 Display Unit LEDs
The display unit has two LEDs, one green and one amber. The green LED indicates that data
compression is active. The amber LED is a user-programmable, error-alert indicator that lights when
the error-rate percentage reaches a predetermined value. This value may be set and/or altered using the
mode switch in conjunction with the setup menus.