Before you begin your installation

About disk shelf installation

Before you install one or more disk shelves in a rack, you need to understand the following information:

Disk shelf numbering
Loop IDs
Supported disk drives
Drive bay requirements

Disk shelf numbering

Each disk shelf in a loop must have a unique ID. A valid shelf ID is from 1 through 7, with disk shelf 1 connected to the storage appliance. If you install a second or third loop of disk shelves, the disk shelf IDs in each loop must start at 1. The ID of a single disk shelf must be 1.

Note
When connecting a DS14 to a preexisting mixed-shelf loop, the DS14 disk shelf ID must be higher than any of the disk shelves already in the loop.

Each disk shelf is shipped with its assigned ID set on its back panel. You must ensure that the disk shelf has the correct ID number on the label. The ID label is on the right side of the disk shelf, as shown in the following illustration.

Network Appliance sets the disk shelf IDs at the factory on configured systems, using an ID switch on the back panel. If you order additional disk shelves, you must set the disk shelf ID.

Note
If you enter a shelf ID that is not from 1 through 7, the drive addresses will default to those of a shelf with the ID switch set to 7 even though the Shelf ID indicator in the front operation panel will display a dash (-).

The example in the following illustration shows s DS14 with the disk shelf ID set to 1.

Loop IDs

In addition to identifying the disk shelf ID and the direction of the drive bays, the ID label on the right side of the disk shelf includes the loop ID. The loop ID identifies the disks in the disk shelf. The following table lists the seven disk shelf IDs and their corresponding loop IDs.

DS14 ID	Loop IDs
7	125-112
6	109-96
5	93-80
4	77-64
3	61-48
2	45-32
1	29-16

Supported disk drives

The DS14 supports 18-GB, 36-GB, and 72-GB block checksum disk drives.

Drive bay requirements

For enclosure services monitoring to work, drive bays 0 and 1 must contain a disk.

This requirement is posted on the label on the left flange of the disk shelf. The 14 drive bays in the disk shelf are numbered 0 through 13 from right to left, as shown in the following illustration.

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

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

Stage	Device	What it does...
1	Storage appliance	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	Storage appliance	Sends the commands through its Fibre Channel interface to drive bays 0 and 1 on the disk shelf.
3	Drive bays 0 and 1	Communicate the request to the LRC module and send the data to the storage appliance.
3	LRC module	Collects the requested data and sends it to drive bays 0 and 1.