Installation and User's Guide

Storage unit drive bays

The following sections describe the hot-swap CRUs, the switch card bay, and the bridge card bay on the storage unit.

With the hot-swap features of the storage unit, you can remove and replace hard disk drives, power supplies/fans, and ESM boards without turning off the storage unit. Therefore, you can maintain the availability of your system while a hot-swap device is removed, installed, or replaced. See "Installing and replacing devices" for more information.

Hot-swap drive bays

The following illustration shows the location of the hot-swap drive bays accessible from the front of your storage unit. The storage unit supports up to 14 IBM Ultra160 SCSI or Ultra2 SCSI hard disk drives. These drives come pre-installed in a drive tray. The drive and tray assembly is called a drive CRU (customer replaceable unit). You can install the drive CRUs in the 14 drive bays on the front of the storage unit.

In the following figure, seven of the 14 bays contain drive CRUs, and seven bays contain filler panels. To maintain proper cooling within your storage unit, always keep a filler panel in each drive bay that does not contain a drive CRU. For information on installing and replacing drive CRUs, refer to "Installing and replacing devices".

Attention: Never hot-swap a drive CRU when its green activity light emitting diode (LED) is flashing. Hot-swap a drive CRU only when its amber fault LED is lit (not flashing) or when the drive is inactive with the green activity LED off (not flashing).

Bridge card bay

The bridge card is accessible from the front of the unit. You can replace the bridge card CRU, but you must turn off the storage unit before doing so. Refer to "Replacing a bridge card" for step-by-step instructions.

Attention: Never remove the bridge card while the storage unit is turned on. Refer to "Switching the storage unit on and off".

ESM and power supply bays

The following illustration shows the location of the environmental services monitor (ESM) bays (for the hot-swap ESM boards) and the power supply bays where the hot-swap power supplies are located.

Hot-swap ESM bays

The ESM boards provide a SCSI interface to the drives and monitor the overall status of the storage unit. Refer to "Replacing an ESM board" for more information.

Hot-swap power supply/fan bays

Your storage unit comes with two 500 Watt hot-swap and redundant power supplies with built-in fans. The power supplies are redundant in that a single power supply can provide adequate power and cooling for the entire storage unit. A single power supply can support up to 14 hard disk drives; however, both power supplies must be installed, even if one power supply is not operational. Refer to "Working with hot-swap power supply/fan units", for step-by-step instructions.

Switch card bay

Your storage unit comes with a switch card that contains five external option switches and four internal option switches. The switch card is located on the back of the storage unit between the two power supplies. The switch card contains switches that control how power is supplied to the storage unit and what storage unit services are enabled. The internal option switches are preset to the default position (Off). To access the four internal option switches, you must turn off the storage unit; then remove the switch card. Refer to "Replacing the switch card", for step-by-step instructions.

Attention: Never remove the switch card or change the switch card settings while the storage unit and host server is turned on. Refer to "Switching the storage unit on and off".

In addition to the internal and external option switches, the switch card also has a 10-position unit ID switch for setting the storage unit ID using values 0 through 9. System-management software, such as IBM Netfinity Manager^(TM), uses the ID when it provides data and alerts for the storage unit.

For more information on option switch settings, see "Setting the interface options and ID settings".

The following illustration shows the location of the switch card on the storage unit.