[ltp] Does hdaps [APS] work on non-Thinkpad hard drives?

[Jon Escombe]

r8scq7b02@sneakemail.com wrote:
> Hello,
> 
> My understanding of APS [Active Protection System] on supprting Thinkpad laptops is that the mechanism detects movement and when it reaches a critical level, the APS, via software, parks the drive heads.
> 
> However, according to the ThinkWiki problem page [1], there are problems with non-Thinkpad branded hard drives. To quote:
> Additionally, the following ATA commands are implemented by ThinkPad-branded drives but are not supported by most other laptop drives: 
> UNLOAD IMMEDIATE (needed for the Active Protection System) 
> SECURITY FEATURE SET (needed for disk password protection)
> 
> Is this correct? How can other hard drives not be supported by APS if all it does is park the heads, which every hard drive can do?
> 
> Is UNLOAD IMMEDIATE something that exists in only a few hard drives? And is it even required for APS to function correctly as the ThinkWiki suggests?
> 
> [1] http://www.thinkwiki.org/wiki/Problem_with_non-ThinkPad_hard_disks#Problem_Description
> 
> Thank you.

Hi,

The difference is between parking the heads with UNLOAD_IMMEDIATE and 
putting the drive into standby with STANDBY_IMMEDIATE - which also parks 
the heads - but is slower and causes more wear & tear on the drive.

Unload immediate is part of the ATA spec, but not all drives support it, 
and some that do don't even report the support correctly. However, the 
HDAPS patches can override the detection if you know for sure what your 
drive supports.

Regards,
Jon.