High Quality Content by WIKIPEDIA articles! The introduction of Serial Attached SCSI (SAS) as the most recent evolution of SCSI required to re-define the related standard for enclosure management, called SCSI Enclosure Services . SES-2, or SCSI Enclosure Management 2 first revision was introduced in 2002 and is now at revision 20. SES-2 SCSI Enclosure Services (SES) permit the management and sense the state of power supplies, cooling devices, LED displays , indicators, individual drives, and other non-SCSI elements installed in an enclosure. SES2 alerts users about drive, temperature and fan failures with an audible alarm and a fan failure LED.