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10.18 SCT Command Transport feature Set
10.18.1 Overview
10.18.1.1 Introduction
SMART Command Transport (SCT) is the method for the drive to receive commands using log page E0h and
transporting data using log page E1h. These log pages are used as follows:
Table 38 SCT Log Page and direction
Log page E0h
Log Page E1h
Write log page
Issue Command
Send Data to the drive
Read log page
Return Status
Received Data from the drive
There are two ways to access the log pages: using SMART READ/WRITE LOG and READ/WRITE LOG EXT. Both
sets of commands access the same log pages and provide the same capabilities.
The log directory for log pages E0h and E1h should report a length of one. The length of log page E1h does not
indicate the length of an SCT data transfer.
If SMART is supported, but not enabled, the drive supports SMART READ/WRITE LOG for Log page E0h and E1h.
If security is enabled and password has not been issued to unlock the device, all SCT commands will fail. 10.18.1.2 Capability definition
Capability Identification is performed by issuing Identify Device command. Word 206 of Identify Data is used to
determine if SCT is enabled and which SCT Action Codes are supported.
Table 39 Identify Device Information Word 206
Word
Description
206
SCT Command set support
15-12
Vendor Specific
11-6
Reserved
5
Action Code 5 (SCT Data Table) supported
4
Action Code 4 (Features Control) supported
3
Action Code 3 (Error Recovery Control) supported
2
Action Code 2 (SCT Write Same) supported
1
Obsolete
0
SCT Feature Set supported (includes SCT status)
85
Hard Disk Drive Specification