User`s guide

StorageWorks SCSI Buses

5.1 Assigning Device Addresses

Use the following rules and procedures to assign device addresses to the SBBs

(disk drives, tape drives, and so forth).

CAUTION

Each device address on a SCSI bus can only be used once.

Each device address on an SBB shelf can only be used only once unless

the shelf has multiple buses and the SBBs have device address switches.

• The SBB device address for the 3½-inch tape SBBs and all 5¼-inch SBBs is

determined by the address switch on the rear of the SBB. When the address

switch is set to the automatic position, the address is determined by the

physical location in the shelf. When these switches are set to any other valid

address, the SBB shelf connector device address is disabled.

• Before installing the SBB in the shelf, set the switches on the rear of the SBB

to one of the addresses shown in Table 5–1.

Table 5–1 SBB Device Address Switch Settings

Switch Number

Address 1 2 3 4 5 6

0 OFF OFF OFF OFF OFF OFF

1 ON OFF OFF OFF OFF OFF

2 OFF ON OFF OFF OFF OFF

3 ON ON OFF OFF OFF OFF

4 OFF OFF ON OFF OFF OFF

5 ON OFF ON OFF OFF OFF

6 OFF ON ON OFF OFF OFF

7† ON ON ON OFF OFF OFF

Automatic‡ OFF OFF OFF ON ON ON

† Normally reserved for the host.

‡ Sets the device address to the shelf default value.

• A 5¼-inch SBB can contain one full-height (FH) or two half-height (HH)

devices. To set the device addresses for a 5¼-inch SBB with two HH devices

installed (see Figure 5–2):

– Use the center switch to set the lower device address switch.

– Use the left switch to set the upper device address.

Note

Only the center switch is installed when there is a FH 5¼-inch device or

only one HH 5¼-inch device in a 5¼-inch SBB.

5–2 StorageWorks SCSI Buses