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Kristen Carlson Accardi - Intel Corporation

SATA Blinky Lights

When you have large piles of disks to manage, you need to have some visual way to distinguish individual disks physically, and associate them with the logical representation you see exposed on your system. Typically this is achieved with LEDs, via some specified enclosure management protocol.

Not only are there multiple enclosure management protocols that a single piece of hardware could support, but multiple types of hardware may wish to utilize the same protocol. With SATA devices becoming more and more common for enterprise systems, SATA chipsets are beginning to support communication to disk enclosures to enable enclosure management applications, as well as SAS or SCSI. In particular, the AHCI specification defines several mechanisms for SATA host controllers to support enclosure management for disk devices.

In order to allow drivers to share many different types of enclosure management protocol routines, a general purpose enclosure management driver interface is required. This talk will cover the generic enclosure management interface, and then show two specific implementations of enclosure management protocols that utilizes this interface, using the ahci driver as an example low level driver implementation.

We'll cover the basic interfaces that need to be defined per protocol, then how to utilize these interface in a low level driver. We'll very briefly touch on the specifics of the protocols that have been implemented, and finally we will discuss how management applications can communicate with the kernel to control LED behavior for each protocol.