Installing an R150 disk shelf

Disk shelf fundamentals

Supported disk drives

Each R150 disk shelf supports twelve 250-GB ATA hard disk drives with an actual storage capacity of 212 GB per hard drive after formatting.

Disk drive labeling

Each disk drive is labeled with a unique SCSI address, which helps define its location within the disk shelf. Addresses are assigned to each drive bay beginning right to left in four groups, corresponding to the disks supported by each bridge in the disk shelf.

	SCSI address	Drive bay number
Bridge 1	0	0
	1	1
	2	2
	3	3
	4	SES device
reserved	5	unused
	6	unused
	7	SCSI adapter
Bridge 2	8	4
	9	5
	10	6
	11	7
Bridge 3	12	8
	13	9
	14	10
	15	11

Therefore, the 12 drive bays in the disk shelf are labeled between 0 and 15 from right to left with SCSI addresses 4, 5, 6, and 7 reserved for other internal functions. The SCSI address labels are shown in the following illustration.

Enclosure services monitoring

The R150 uses the enclosure services monitoring method to monitor environmental conditions of the disk shelf. Enclosure services conditions are communicated to the storage engine through the EMU module.

The following table describes the four stages of enclosure services monitoring.

Stage	Device	What it does...
1	Storage engine	Uses a subset of SCSI-3 commands to monitor the disk shelf for data related to disk presence, temperature, power supply units, and fan status.
2	Disk shelf	The SCSI-ATA bridge requests information from the EMU.
3	Disk shelf	The EMU returns the environmental data to the bridge.
4	Disk shelf	The bridge returns EMU data to the storage engine.