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EX800M
3.11 S.M.A.R.T. Command Transport (SCT)
The SCT Command Transport feature set provides a method for a host to send commands and data to
a device and for a device to send data and status to a host using log pages. Standard ATA commands
may be interspersed with SCT commands, but SCT commands cannot be nested. SCT commands that
do not require a subsequent data transfer operation are not interspersed with any ATA commands or
each other.
The SCT Command Transport feature set provides a method for a host to send commands and data to
a device and for a device to send data and status to a host using log pages. This capability is used to pass
commands through a driver interface or a bridge where new or unknown commands may be filtered
and not passed to the drive. SCT is also used for issuing commands that require more than 8 parameter
bytes. ATA8-ACS provides detailed information on the usage and capabilities of SCT. The SCT
feature set includes the following commands:
Write Same
Temperature Reporting
3.11.1 Write Same
The Write Same command allows the host to erase the media, or write a pattern repeatedly across the
media, with a minimum of data transfer from the host. The host can clear the entire media to zeros or
a specific pattern by sending this command with the pattern as a parameter—no data transfer is
necessary. Write Same can write the entire media, or just a portion of the media. The host can monitor
the progress of the Write Same by issuing SCT Status requests. This frees the host system to do other
tasks while the media is being cleared.
3.11.2 Temperature Reporting
The SCT Temperature Reporting (SCT TR) feature allows a host system to access temperature
information in the drive. The S.M.A.R.T. temperature value is reported within ±3°C of the base
casting temperature. This information can been used to control fans or adjust the usage of various
system components to keep the drive within its normal operating temperature. Applications include
Enterprise, Laptop, Desktop and Consumer Electronics. SCT TR reports the maximum and minimum
sustained operating limits, warning level limits, and drive damage limits. In addition to reporting the
limits, SCT TR returns the current drive temperature (a temperature history which the host can use to
predict heating or cooling trends) and the maximum temperature acheived during the lifetime of the
drive as well as the highest temperature achieved since the power was applied to the drive. Detailed
information on this capability can be found in ATA8-ACS.
3.12 World Wide Name (WWN)
It has become a critical requirement that hard drives be uniquely identified by computer systems. This
allows a drive to maintain its identity as it is transported from system to system or placed on a network.
IEEE has defined a format for serial numbers that is widely recognized in the computing industry by
adding World Wide Name (WWN) to ATA/ATAPI-7 in 2002.
The World Wide Name (WWN) defined in ATA/ATAPI-7 is a modification of the IEEE Extended
Unique Identifier 64 bit standard (EUI-64) and is comprised of three major components: naming
authority, organizationally unique identifier (OUI) and serial number. WD's OUI is 0014EEh.
3.13 Hot Plug Support
SATA supports hot plugging (also known as "hot swapping"), the ability to swap out a failed hard drive
without having to power down the system or reboot. This capability contributes to both data
availability and serviceability without any associated downtime, making it a critical feature for
extending SATA into enterprise applications.
2679-771339-A05
RELEASED 8/13/13
Product Features
21
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