简介：
In computer storage, a SCSI Accessed Fault-Tolerant Enclosure is an industry standard to interface an enclosure to a (parallel) SCSI subystem to gain access to information or control concerning
- temperature
- fan status
- slot status (populated/empty)
- door status
- power supplies
- alarms
- indicators (e.g. LEDs, LCDs)
Practically, any given SAF-TE device will only support a subset of all possible sensors or controls.
Many RAID controllers can utilize a SAF-TE ‘activated’ backplane by detecting a swapped drive (after a defect) and automatically starting a rebuild. A passive subsystem usually requires a manual rescan and rebuild.
A SAF-TE device is represented as a SCSI processor device that is polled every couple of seconds by e.g. the RAID controller software. Due to the low overhead required, impact on bus performance is negligible. For SAS or Fibre Channel systems, SAF-TE is replaced by the more standardized SCSI Enclosure Services.
The most widely used version was defined in ‘SAF-TE Interface Specification Intermediate Review R041497 April 14, 1997′ by nStor (now Xyratex) and Intel.
以下摘录自intel网站
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 status such as ‘rebuilding’, ‘fault’, and ‘hot spare’. The SAF-TE status setting commands are typically issued either by an intelligent disk controller, or by software, e.g. 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 (SR041497.pdf) 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 as of this writing the domain “www.safte.org” referenced in the specification is no longer active.
Note that a number of enclosure implementations have been based on the 08/27/96 revision (SR082796.pdf) of the specification. This version was the original SAFTE 1.0 specification plus addenda. These documents, plus documents highlighting the differences against the 04/14/97 version are included in the SAFTEarchive.ZIP file. It is highly recommended that software and controllers make provision for differences between the versions.
参考网站
http://www.safte.org/
http://storagesecrets.org
