A couple of week ago I built my first media PC. One of the main requirements for this computer was that it should be silent. So far I’ve been testing different software to get the best media PC functionality and finally ended up using Media Portal with a few plugins and tweaking some Windows settings.

Leaning back on the couch ready to enjoy my new media center I discovered that there is disk access every few seconds even when the system is idling (no media center activity). This is totally unacceptable as disk activity generates both noise and HDD led flash (additionally there should be no reason for the constant disk access).

Time for some diagnostics.

1) Check that the windows indexing function is turned off.
- Yes, it is!

2) Download and install Process Explorer http://www.microsoft.com/technet/sysint ... lorer.mspx

3) Discover which process is the culprit.
- lsass.exe
- csrss.exe
- Div. Avast Home Edition services (my antivirus solution)

Assuming that lsass and csrss activity was caused by the antivirus activity I stopped all antivirus processes, set them to manual start and rebooted. Result…
… no antivirus processes causing disk access, but still disk access from lsass.exe and csrss.exe.

After googling a bit I discover this gem.

http://malektips.com/xpwtw0015.html

Basically telling me that Windows optimizes my harddisk whenever the computer is idle.

I download and install Tweak UI, uncheck "Optimize hard disk when idleâ€

AVG Anti-Virus (grisoft.com). Latest version is 7.5.

Let it blink. What does it matter if a light blinks?

A randomly blinking light can be almost as distracting as a loud noise, especially for an HTPC. But the solution is simple, just unplug the HDD LED.

I just want to know what causes it,my windows has the same led blinking every time.

But my other pc does it also, and the only thing it has connected to the ide controller is a cdrom drive.
The led is just blinking every 10-20 secs.
(the disk drive is connected to a promise controller, with it's own led (disconnected)).
I haven't had the time to test it, but maybe the cdrom drive is causing this behaviour?

I've noticed this on a recent build with an nVidia MB chipset (MSI) - fresh XP-SP2 install with no tweaking. The drive light flashs like a heartbeat - about once a second. On an old Dell GX240 SFF (P4 2MHz) which has a relatively fresh XP-SP2 install, the light is dark for minutes at a time. Neither have anti-virus.

Although I don't know the precise details, this light is controlled by the MB - not necessarily the drive. The MB might be manipulating the signal somehow...

Soooooooo, why don't you just disconnect the HD LED? Personally, I don't usually plug in that one anyways. How often do I need to see that the HD is working?

And why are you worried about Anti-Virus on an HTPC? I would assume you wouldn't be installing too many applications once it's up and running. And installing bad software is where most viruses/malware come from these days. So the possibility of a virus infection seems rather low to me.

Well, I just want to know what my computer is doing, nothing else.

It's vaguely like unplugging the tach in your car. It isn't needed for general operation but it's good to know what's going on - it can be a warning of something unusual.

If you have a SATA HDD, you could try to change the "write caching and safe removal" settings in the device manager. In the device manager, double-click on your HDD to access its properties, then under the "Policies" tab, make sure that "Optimize for quick removal" is selected. By default, the other option is selected, allowing Windows to optimize the drive in background when the system is idle.

Disabling write-caching can result in plenty more thrashing. The noise-penalty might not be worth it.

Have the same problem on a brand new installation. (XP Pro, SATA HD, SATA DVD). No process or file can be indicated. The HD led is flickering about every second!?

The suggestion of turning off the disk LED (and similar approached) is not really serious, or is it? Would you turn off (unplug) your empty gastank indicator? What about the sirens when the message "This spacestation will selfdestruct in T minus 3 minutes!"?

I also "just" would like to know!

I put a piece of blue masking tape over the light and cut it so it just covered the LED. This makes the light so dim that it does not bother me but I can still tell it is blinking. As for the random blinks, yeah, mine does that too. I tried to figure out what it is doing and just gave up.

I was absolutely serious. If you want to know if it is reading, put your head next to the case.

Hmm, my memory must be bad, I seem to recall suggesting that...

That is not necessarily true. If the hard disk is reading from it's cache or when it is reading from the places it heads are already positioned at, then it wouldn't make a sound, but it is reading / writing something.

Therefore the sound of the hard disk is not a good measurement of disk activity.
That is exact the reason they invented the led

"Put your ear to the case.."
My case is on the floor, and I do not need the exercise. I do not constantly watch and aggravate myself about the behaviour of the LED! It is not the light what bothers me. It is that I do not know what it does, why it does it, and that it is so hard to find information about it. It may be only the tip of an iceberg, and your system might be slower in many other ways. The light is only a symptom not the real problem.
I have an MSI K9N motherboard with an NVIDIA (ver. 5.10.2600.666 - "not the best of signs!"!?) driver for the SATA drives. That is my next line of research.

I have an Epox NF4. I've found the the HDD light illuminating every few seconds is actually caused by the optical drive. My optical drive is SATA-based, so when I get tired of the light and I'm not using the optical drive, I can use the 'Safely Remove Hardware' to stop the drive from lighting up the LED. Now if you have a PATA optical drive, try physically disconnecting it and seeing if the same behavior occurs.

Good luck.

Mine does the same thing - I've investigated every possibility I can think of, and it's some process I can't identify associated with csrss.exe writing a few bytes to the disk every second or so.

In the end I just gave it up as a bad job and went to the pub. I'm sure the tiny amount of activity isn't harming the HDD in any way, and I very much doubt it's hurting performance, but I agree with you it's annoying not knowing what it is...