Software Setting Preservation - Hitachi CinemaStar P7K500 Specifications

8.19 Software Setting Preservation

When a device is enumerated, software will configure the device using SET FEATURES and other
commands. These software settings are often preserved across software reset but not necessarily across
hardware reset. In Parallel ATA, only commanded hardware resets can occur, thus legacy software only
reprograms settings that are cleared for the particular type of reset it has issued. In Serial ATA,
COMRESET is equivalent to hard reset and a non-commanded COMRESET may occur if there is an
asynchronous loss of signal. Since COMRESET is equivalent to hardware reset, in the case of an
asynchronous loss of signal some software settings may be lost without legacy software knowledge. In
order to avoid losing important software settings without legacy driver knowledge, the software settings
preservation ensures that the value of important software settings is maintained across a COMRESET.
Software settings preservation may be enabled or disabled using SET FEATURES with a subcommand
code of 06h. If a device supports software settings preservation, the feature shall be enabled by default.
8.19.1 COMRESET Preservation Requirements
The software settings that shall be preserved across COMRESET are listed below. The device is only
required to preserve the indicated software setting if it supports the particular feature/command the setting is
associated with.
I NITIALIZE DEVICE PARAMETERS:
U
PARAMETERS command.
P ower Management Feature Set Standby Timer:
U
feature set.
R ead/Write Stream Error Log:
U
using READ LOG EXT and WRITE LOG EXT).
S ecurity mode state:
U
(refer to section 6.13 of the ATA/6 specification). The device shall not transition to a different security
mode state based on a COMRESET. For example, the device shall not transition from the SEC5:
Unlocked / not Frozen state to state SEC4: Security enabled / Locked when a COMRESET occurs,
instead the device shall remain in the SEC5: Unlocked / not Frozen state.
S ECURITY FREEZE LOCK:
U
command.
S ECURITY UNLOCK:
U
command attempt.
S ET ADDRESS MAX (EXT):
U
MAX EXT.
S ET FEATURES (Write Cache Enable/Disable):
U
the SET FEATURES command with subcommand code of 02h or 82h.
S ET FEATURES (Set Transfer Mode):
U
by the SET FEATURES command with subcommand code of 03h.
S ET FEATURES (Advanced Power Management Enable/Disable):
U
management enable/disable setting established by the SET FEATURES command with subcommand
code of 05h or 85h. The advanced power management level established in the Sector Count register
when advanced power management is enabled (SET FEATURES subcommand code 05h) shall also be
preserved.
S ET FEATURES (Read Look-Ahead):
U
SET FEATURES command with subcommand code of 55h or AAh.
S ET FEATURES (Reverting to Defaults):
U
established by the SET FEATURES command with a subcommand code of CCh or 66h.
S ET MULTIPLE MODE:
U
HITACHI Deskstar & CinemaStar P7K500 Hard Disk Drive specification (Rev 1.1)
Device settings established with the INITIALIZE DEVICE
U
The Read Stream Error Log and Write Stream Error Logs (accessed
U
The security mode state established by Security Mode feature set commands
U
The Frozen mode setting established by the SECURITY FREEZE LOCK
U
The unlock counter that is decremented as part of a failed SECURITY UNLOCK
U
The maximum LBA specified in SET ADDRESS MAX or SET ADDRESS
U
PIO, Multiword, and UDMA transfer mode settings established
U
The read look-ahead enable/disable setting established by the
U
The reverting to power-on defaults enable/disable setting
U
The block size established with the SET MULTIPLE MODE command.
U
87
The Standby timer used in the Power Management
U
The write cache enable/disable setting established by
U
The advanced power
U