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Western Digital and some other HDD makers have been offering for some time Power-up in standby (PUIS) feature in their Hard Drive product lines. This is considered Enterprise RAID product class feature, nonetheless very useful in Workstations and Desktops, including older PCs with multiple drives and weaker PSUs. It requires BIOS support. When activated, it allows to waken up non-system HDDs into Standby (non-spin) mode at PC wakeup from Standby or Hibernation. Meaning, they won't start spinning at PC wakeup right away, but instead will wait until you try to open a file saved on that HDD or save a file onto it. Otherwise the HDD will follow usual power management cycle during PC operation, meaning it will stop spinning when not accessed for a set time period.
This is a great power saving feature, it prolongs HDD and PSU service life, and allows to avoid voltage & current spikes and drops at simultaneous multiple drive spin-ups, leading to PC wakeup delays and BSODs resulted from delayed access to a system HDD, and causing faster PSU wearing. The feature is described in more details in Working Draft ATA/ATAPI Command Set - 2 (ACS-2):
"The PUIS feature set allows devices to be powered-up into the Standby power management state to minimize
inrush current at power-up and to allow the host to sequence the spin-up of devices . This optional feature set
may be enabled or disabled via the SET FEATURES command; may be enabled by use of a jumper or similar
means, or both . When enabled by a jumper, this feature set shall not be disabled via the SET FEATURES
command . The IDENTIFY DEVICE data or IDENTIFY PACKET DEVICE data indicates whether this feature set
is implemented and/or enabled.
Once this feature is enabled in a device, the device shall not disable the feature as a result of processing a power
cycle, a hardware reset, or a software reset.
A device may implement a SET FEATURES subcommand (see 7.50.8) that notifies the device to spin-up to the
Active state when the device has powered-up into Standby . If the device implements this SET FEATURES
subcommand and power-up into Standby is enabled, the device shall remain in Standby until the SET
FEATURES subcommand is received . If the device implements this SET FEATURES subcommand, the fact
that the feature is implemented is reported in the IDENTIFY DEVICE data or IDENTIFY PACKET DEVICE data.
If the device:
a) implements the Enable/disable Power-up in Standby subcommand;
c) has the PUIS feature set enabled; and
d) receives an IDENTIFY DEVICE command or IDENTIFY PACKET DEVICE command while the device is
in the Standby power mode as a result of powering up in that mode,
then the device shall respond to the IDENTIFY DEVICE command or IDENTIFY PACKET DEVICE command
without spinning up the media . If the device is unable to return a complete response without accessing the
media, then the device shall set IDENITFY DEVICE data word 0 bit 2 to one to indicate that the response is
incomplete . At a minimum, IDENITFY DEVICE data word 0 and IDENITFY DEVICE data word 2 shall be
correctly reported . Those fields that are not provided shall be filled with zeros . Once a device is able to return
all data for an IDENTIFY DEVICE command or IDENTIFY PACKET DEVICE command, the device shall return
all data for those commands until after processing the next power cycle.
If the device does not implement the SET FEATURES subcommand to spin-up the device after power-up and
PUIS is enabled, the device shall spin-up upon receipt of the first command that requires the device to access
the media, except the IDENTIFY DEVICE command or the IDENTIFY PACKET DEVICE command."
PUIS can be set (activated) by setting a jumper on each HDD or using a special software tool, if PUIS is supported by your MoBo BIOS and firmware & hardware of your drive models - check your HDD specs to find it out (if not listed in the spec, you may try anyway). Western Digital offers WD SATA and EIDE Hard Drives Jumper Settings Guide for their models. One of reliable tools to activate PUIS by standard commands is offered by Hitachi, and can also be safely used for other HDD makes like Seagate HDDs: Hitachi Feature Tool. There are other tools found on the web capable to activate PUIS.
I wonder if someone used this feature or any brand make tools or jumpers for PUIS activation, and can share your experience, what 3.5' or 2.5' HDD models you found supporting this feature, what tools used to activate it, and any problems faced.
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