Put some information (and pointers to more) into the kernel's doc tree, describing briefly how to set up disk shock protection under GNU/Linux. Signed-off-by: Elias Oltmanns <eo@xxxxxxxxxxxxxx> --- Documentation/laptops/disk-shock-protection.txt | 66 +++++++++++++++++++++++ 1 files changed, 66 insertions(+), 0 deletions(-) create mode 100644 Documentation/laptops/disk-shock-protection.txt diff --git a/Documentation/laptops/disk-shock-protection.txt b/Documentation/laptops/disk-shock-protection.txt new file mode 100644 index 0000000..ac26040 --- /dev/null +++ b/Documentation/laptops/disk-shock-protection.txt @@ -0,0 +1,66 @@ +Hard disk shock protection +========================== + +Author: Elias Oltmanns <eo@xxxxxxxxxxxxxx> +Last modified: 2008-07-24 + + +Intro +----- + +ATA/ATAPI-7 specifies the IDLE IMMEDIATE command with UNLOAD FEATURE. +Issuing this command should cause the drive to switch to idle mode and +unload disk heads. This feature is being used in modern laptops in +conjunction with accelerometers and appropriate software to implement +a shock protection facility. The idea is to stop all I/O operations on +the internal hard drive and park its heads on the ramp when critical +situations are anticipated. The desire to have such a feature +available on GNU/Linux systems has been the original motivation to +implement a generic disk head parking interface in the Linux kernel. + + +The interface +------------- + +The interface works as follows: Writing an integer value to +/sys/block/*/device/unload_heads will take the heads of the respective +drive off the platter and block all I/O operations for the specified +number of seconds. When the timeout expires and no further disk head +park request has been issued in the meantime, normal operation will be +resumed. + +FIXME: +Once we've addressed the problem with pre-ATA-7 drives supporting the +UNLOAD FEATURE but not announcing it properly, we'll document it +accordingly. + + +References +---------- + +There are several laptops from different brands featuring shock +protection capabilities. As manufacturers have refused to support open +source development of the required software components so far, Linux +support for shock protection varies considerably between different +hardware implementations. Ideally, this section should contain a list +of pointers at different projects aiming at an implementation of shock +protection on different systeems. Unfortunately, I only know of a +single project which, although still considered experimental, is fit +for use. Please feel free to add projects that have been the victims +of my ignorance. + +- http://www.thinkwiki.org/wiki/HDAPS + See this page for information about Linux support of the hard disk + active protection syystem as implemented in IBM/Lenovo Thinkpads. + (FIXME: The information there will have to be updated once this + patch has been approved or the user interface has been agreed upon + at least.) + + +CREDITS +------- + +This implementation of disk head parking has been based on a patch +originally published by Jon Escombe <lists@xxxxxxxxxxxx>. Assisted by +various kernel developers, the author of this document has rewritten +the original patch in order to make it fit for upstream submission. -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
