What are the best practices of shelf numbering for attaching SAS shelves to a storage system?

What are the best practices  of shelf numbering  for attaching SAS shelves to a storage system?

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Each SAS shelf directly attached to a High-Availability (HA) controller pair, or to a standalone non-HA controller, requires a unique Shelf ID in the range 0-98. In instances where the node contains internal disks, the internal shelf is set to ID 0, leaving ID's 1-99 available for external shelves.

In an ONTAP 9 environment, the shelf IDs only need to be unique within an HA pair, not across the entire cluster.
For example, if HA pair Node01/Node02 used Shelf ID 10, then HA pair Node03/Node04 may also use Shelf ID 10, if so desired.

Note that when Shelf IDs are repeated across a cluster, extra care should be taken to ensure that any maintenance required is performed on the correct shelf - such as verifying the shelf serial number - and not relying soley on the Shelf ID for identification.

Note: NetApp recommends numbering shelves in stacks by the 10's rule.

For controllers with no internal disks, the numbering would be as follows:

Nodes 1/2:

• Stack 1 contains shelf ID's 0-9
• Stack 2 contains shelf ID's 10-19

Nodes 3/4:

• Stack 1 contains shelf ID's 20-29
• Stack 2 contains shelf ID's 30-39

In the case of controllers with internal disks (e.g. AFF A150) the shelf ID of the controller chassis is 0. The numbering would be as follows:

Nodes 1/2:

• Stack 1 contains shelf ID's 1-9
• Stack 2 contains shelf ID's 10-19

Nodes 3/4:

• Stack 1 contains shelf ID's 20-29
• Stack 2 contains shelf ID's 30-39