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SCSI Accessed Fault Tolerant Enclosures

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SAF-TE: SCSI accessed fault tolerant enclosures interface specification

This specification defines a set of SCSI commands for setting drive status information, including status for RAID arrays, into a disk drive array enclosure. The drive array enclosure may be a separate enclosure, or the same enclosure. The specification also defines commands for managing hot-swap drive slots and returning environmental health information for a drive enclosure.

The status commands are typically used by the enclosure manufacturer to assert lights or other indicators that provide information to the user about the state of the drives in the array. This can include statuses such as "rebuilding," "fault," and "hot spare." The SCSI accessed fault tolerant enclosures (SAF-TE) status setting commands are typically issued either by an intelligent disk controller or by software—for example, RAID software—running under the operating system. Other parties on the SCSI bus may elect to access the status information as a means of determining the state of the physical drives in the array.

In addition, SAF-TE commands can be used to report certain environmental information about the enclosure, such as temperature, voltage, power supply, and fan health.

While the 04/14/97 revision is marked "Intermediate Review," this document is the de-facto and most widely deployed version of the specification and is recommended as the basis for any new implementations. 

Note that a number of enclosure implementations have been based on the 08/27/96 revision of the specification. This version was the original SAF-TE, V1.0, specification plus addenda. These documents, plus documents highlighting the differences against the 04/14/97 version, are included in the SAF-TE Archive Zip* file. It is highly recommended that software and controllers make provision for differences between the versions.