HP SureStore E Disk Array 12H User's and Service Manual (C5445-90901, September 1999)

Removal and Replacement
Backplane Assembly–HP-qualified personnel only
197
Removal
SCSI Bus Reset Switches–HP-qualified personnel only
CAUTION! After replacing the backplane assembly, make sure that the SCSI bus reset
switches are set as shown in Figure 33. Altering the default factory settings on the SCSI
bus reset switches may cause operating system conflicts for the host computer(s).
The SCSI bus reset switches (see Figure 33) are located on the top-left corner of the backplane assembly.
To locate the switch, remove the rear cover to expose the switch. Figure 33 shows the switch segments on
the SCSI bus reset switch and Table 15 shows the switch functions.
The SCSI bus reset switches are preset at the factory for proper operation. A SCSI bus reset is a very high
priority interrupt. The SCSI bus reset option is used when the host controller or software requires a SCSI
bus reset to be sent as notification of the removal of a controller or of a power shutdown.
The default setting for the SCSI bus reset switch is shown in Figure 33. There are two switches for each
bus; one switch for power detect and the other is for controller detect. When enabled, the SCSI bus is reset
when the following conditions occurs:
Power detect conditions:
•
The power switch is cycled.
•
When power is first applied (power on).
•
When all power is removed (power off).
Controller detect conditions:
•
A controller module is removed.
•
A controller module is inserted.
The following actions will not cause a power or controller detect (reset) condition:
•
Removing, replacing, or adding a single power module if there are two additional functioning power
modules in the enclosure. A single power module is not sufficient to operate a fully loaded disk array.
•
Removing a fan module.
NOTE! Removing a single fan module will power off the disk array.