Thread: Get HDD Activity

A very interesting project, if you have plenty of time and a spare PC that you don't mind re-installing the OS a few times onto. [As no doubt, you will mess up at some point or another and make the disk completely corrupt].

If you have a lot of Windows programming experience you would realize that you need a filter driver for the hard-disk, and in that filter driver "hook" into the read/write operations, send a message (signal an event) to a service that can flash the LED on the keyboard.

Sending messages to the keyboard is VERY slow (as in, it takes many milliseconds), so you would need to design your service process in such a way that it just ignores any activity going on in between one flash and another of the keyboard LED - since the read/write operations can be queued to the hard-disk much faster than the LED can flash.

You can send commands to set the LED's with IOCTL_KEYBOARD_SET_INDICATORS: http://msdn.microsoft.com/en-us/library/ms791035.aspx

Edit: http://www.codeguru.com/cpp/w-p/syst...icle.php/c2825 shows how you flash the LED lights.

This project is far from "easy" in the sense that it is very easy for any of these operations to cause the entire machine to go wrong if you do not know EXACTLY what you are doing - and as I started out, you will most likely need to reinstall the OS a few times as you've messed something up (crashed the driver when it's in the middle of updating sosmething would be a classic).

Another, much simpler, option would just be to twine a cable with an LED at the end to the keyboard from the machine itself and connect that cable into the LED connector on the machine.

Edit2: You may be able to simplify the process if you use some sort of monitoring/performance counter interface in a service/process - that will not tell the EXACT behaviour at the driver level, but it will give you some idea of what is going on. This solution, combined with the codeguru code above would probably get you something within a few hours.

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Mats

Actually, the HD LED on the front of the case (or wherever it is), is not a BIOS function, but rather a hardware function supported by the hard-disk controller hardware - it is simply a function of the BUSY signal from the hard-disk itself being shown as LED activity. Replacing the BIOS with a completely different set of code will still get the light flashing if you access the hard-disk.

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Mats

Originally Posted by master5001

This may sound convoluted, and like more work than it is worth, BUT here goes. If the light is controlled by the hard-disk controller that means you could design a PCI card that simply captures the output signals and write drivers for your homemade card.

I think this would ultimately be the least intrusive way to monitor the LED. Then we start getting into the "Gee, that sure seems like a lot of work just to keep tabs on a blinking LED." Which really is true, but hey, at least its less invasive as doing something like just running a wire staight to your KB. Which is also always an option.

No, you won't be able to "see" what the BUSY signal on the hard-disk controller is up to on the PCI bus. You could of course connect something to the actual LED connector [most simply a much longer wire with a LED on the end -otherwise you could build a little device to read the level of the connection] on the motherboard [or you could make something that posts a PCI read instructon to the status word of the PATA/SATA controller, and displays bit 7 of that register - but a PCI card is not entirely trivial to build].

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Mats

To do so I need to know a piece of code to "get" the HDD status.

Check out the Diskperf example in the DDK.

EDIT: Instead of toggling the scroll lock light, you might want to put something in the tray area to indicate HDD activity. Check out Sysinternal's Diskmon utility. This utility uses Event Tracing for Windows (ETW) to monitor disk activity and can be minimized to the system tray with a graphic indicator for HDD activity.