IBM manual Enhanced Disk Drive Modules E-DDMs, DS4700 Express hot-swap drive bays

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The hot-swap features enable you to remove and replace 2 or 4 Gbps fibre channel or SATA hard E-DDMs, power supply and fan units, and controllers without turning off the storage subsystem. You can maintain the availability of your system while a hot-swap device is removed, installed, or replaced.

Enhanced Disk Drive Modules (E-DDMs)

The hot-swap drive bays that are accessible from the front of your storage subsystem are shown in Figure 1.

Figure 1. DS4700 Express hot-swap drive bays

The DS4700 Express supports both fibre channel (FC) and SATA E-DDMs intermixed in the storage subsystem drive chassis. The DS4700 Express supports up to sixteen 2 or 4 Gbps fibre channel (FC) or SATA E-DDMs.

SATA E-DDMs have an ATA translator card that converts the fibre channel protocol interface of the DS4700 Express drive channel/loop into the hard drive SATA protocol interface. It also provides dual paths to the SATA drive for drive CRU path redundancy. Each drive, ATA translator card (also referred to as interposer card), and carrier assembly are called SATA E-DDM CRUs. The fibre channel E-DDMs consisted of the fibre channel and the carrier assembly (drive tray).

Install E-DDM CRUs in the 16 drive bays on the front of the storage subsystem from the leftmost slot (slot 1) to the rightmost slot (slot 16). When a E-DDM is installed, the drive and tray slot designation is set automatically. The hardware addresses are based on the enclosure ID, which is set by the controller software, and on the E-DDM's physical location in the storage subsystem.

The DS4700 Express Storage Subsystem drive channel operates at either 2 or 4 Gbps fibre channel interface speed. Ensure that the DS4700 Express enclosure speed switch is set correctly for the 2 Gbps or 4 Gbps fibre channel E-DDM CRUs. The DS4700 Express Storage Subsystem SATA E-DDM CRUs have an ATA translator card that converts E-DDM 3 Gbps SATA drive interface protocol to either 2 Gbps or 4 Gbps fibre channel interface protocol. It is recommended to operate these SATA E-DDMs at 4 Gbps fibre channel operating speed whenever the configuration allows, for example, when no 2 Gbps fibre channel devices are in the configuration. The Link Rate setting speed must be set accordingly. See “Verifying the Link Rate setting ” on page 161 for more information. The enclosure speed of the DS4000 Storage Subsystem must be the same as that of the storage expansion enclosures connected to it.

There are no serviceable parts in an E-DDM CRU. If it fails, it must be replaced in its entirety (E-DDM, ATA translator card, bezel, and tray). The DS4700 Express drive tray is not interchangeable with the drive tray of other DS4000 storage

Chapter 1. Introduction 7