Windows 7 - Hard drive light almost constantly on even when sitting idle

Asked By Jim on 23-Dec-10 08:26 PM
I noticed my hard drive light is now almost constantly on, no matter
if nothing is running, with just the desktop showing.

Doing CTL ALT DELETE I see all kinds of processes running, and tried
to look them up doing google search, but cannot find anything that
I can recognize that might cause this.  My laptop running the same
XP Professional does not do that, when you stop running programs the
hard drive activity light stops.

How can I find out what is causing this and remove it from my
system?  I tried stopping various processes but am afraid to
terminate too many for fear of what might happen.

Would a list of the processes running in the Task Manager help
in diagnosing this problem?  I'd hate to have to do a complete
re-install again, it takes days.



Stan Brown replied to Jim on 24-Dec-10 09:07 AM
Hi. I used to have XP, but now I have Windows 7, so I am not sure this
will be helpful.  But since no one else has replied ...

On the Performance tab of Task Manager, look near the bottom for a
button labeled Resource Monitor.  If you have it, click it for a
utility that shows disk usage by process on one of its tabs.  That is
a bit more focused that simply looking up every process on the
Processes tab of Task Manager, though the latter is possible too.

I had a similar issue in Windows 7, which turned out to be
TrustedInstaller.  But I believe that was introduced in Vista, so it
would not be applicable to you.

However, you still might be experiencing Windows searching for
updates.  You could try changing that to non-automatic. IIRC, you
open the Security Center and click "change how Windows search for
updates" -- I am sorry I cannot be more precise.

It should go without saying, but I will say it -- have you done a
thorough malware scan recently, with definitions up to date?

Stan Brown, Oak Road Systems, Tompkins County, New York, USA
Shikata ga nai...
Jim replied to Stan Brown on 24-Dec-10 05:39 PM

Yes, did Malware, Anti Virus, you name it.

I will check the two items you mentioned, thanks for the input.

Tim Meddick replied to Stan Brown on 24-Dec-10 07:31 PM
I do not think the button you mentioned exists in the XP Task Manager - you
may have been using Win7 to long now to remember.

Under the Performance tab are a Resource Monitor - style "graphical"
bar-meter to show real-time usage for both CPU strain (& running history)
and Page File usage (& running history).

Also, there are four boxes beneath the two "graphical" meters, displaying
constantly updating numerical values for :

Physical Memory (K)
Commit Charge (K)
Kernel Memory (K)

...but again, no "buttons".....

There are no "buttons" under the Resource tab, whatsoever!

On another related matter, perhaps the [free] utility from sysinternals may
be of some [diagnostic] help here...

it is the "Disk Monitor" utility, and once run, can be minimized to the
system tray and acts just like any "Hard-drive lamp" on any PC.  Appearing
red for current disk i/o "writes", green for current "reads" and yellow for

Once copied from it is ZP-file to any place included in your %path%
variable, you can start it already minimised to the system tray from a
registry "Run-Key" command :

diskmon.exe /l

Download the Disk Monitor utility from the sysinternals website at :


Cheers,    Tim Meddick,    Peckham, London.    :-)
Jim replied to Tim Meddick on 25-Dec-10 01:06 PM

Merry Christmas.  That sounds like a  great little utility, it
would at least tell me if the CPU is trying to READ or to WRITE
the drive.  When the drive light is on, there is no change in PAGE
or CPU USAGE usually does not change much, nor is there any NETWORK
activity either, strange.  I disabled the Anti Virus and the Spyware
programs, no luck.  Strange part I have the exact same stuff running
on my Thinkpad, and the drive light rarely comes on unless doing some
other operation.

J. P. Gilliver (John) replied to Jim on 25-Dec-10 02:22 PM

Does the system run slow(ly)? Does the page file figure approach (or
exceed) the amount of fitted RAM?

I have come across systems in/on which the disc light _does_ seem to be
on all the time, even when disc access is not actually occurring. Can you
actually hear whether the disc is being accessed?
J. P. Gilliver. UMRA: 1960/<1985 MB++G.5AL-IS-P--Ch++(p)Ar@T0H+Sh0!:`)DNAf

On the other hand, you have different fingers.
Twayne replied to Jim on 25-Dec-10 05:19 PM
Have you compared the processes list between your laptop and desktop? What
are the differences?
If, say, you are not running background AV searches on the laptop but are
on the desktop, then that explains it all. But be careful; a laptop and
desktop require entirely different sets of system files to be run so you are
looking for programs not of the operatng system.

Download, update and run the following programs (use Google to find them):
Malware Bytes,
MSE from Microsoft, and
Spybot Search and Destroy, and
Start the machine from a cold boot and run each of those one at a time,
keeping track of what they remove. Always allow the programs to save them to
quarantine so you can undo the changes if you need to for troubleshooting
purposes or the addidental removal of something you wanted to keep.
All those programs are free and easy to understand. If you have any
questions about what they find, feel free to ask here before you delete

Maybe; it is hard to say. Autoruns and other such programs might tell a lot
more about what you have there in a more understandable way.

I'd hate to have to do a

Again, why would you consider a full re-install?

Include more information on your system in your response, including RAM
amount, free drive space and drive sizes, anything you think might be
relevant to your situation. And be certain to answer/respond to each point
asked/raised here. It will help others to help you.



It sounds like you have no other problems happening except you noticed the
drive light running a lot more than you expect.
First, this could be normal process such as background AV checks and/or
file indexing in process, especially if you only recently turned it on, or
made a lot of file deletions and/or additions to your system.
There are several other programs that could be running in the background,
thus keeping the drive busy. I have never seen a drive light be on when the
disk was not doing anything; it makes no sense.
These kinds of background tasks automatically stop if you want to use the
computer, allowing you full access to the cpu. it is all quite legitimate in
this case.

Yes, a list of the processes might be useful; it is hard to say and depends
on what they turn out to be.
An easier way to do that sort of thing would be to get Autoruns from and install it. it will give you a lot more
information and makes it easier to test things. Every process windows loaded
at boot is listed, along with information about it.

WHY would you consider a reinstall if there are no other problems? You never
mentioned anything else wrong with your system, so I am betting on the above
being so in this case.
You could, of course, minimize the number of background tasks running but
you will have to figure out what a few of them are and not just kill tasks
willy nilly. 50 Tasks is not an unusual number of tasks to have running in
windows XP.

Another possibility is malware.
Did you update and run your AV program?
Which one do you use?
Tim Meddick replied to Jim on 26-Dec-10 12:27 AM
While it is true that the installed and running Operating System [OS] can
make your machine give "false" readings for the hard-drive lamp, you should
at least be able to tell whether or not the circuitry for the indicator is
intact by observing disk activity shown by it as the system boots-up from a

A "cold-start" being one where the OS has been shut down entirely and not
put into one of the available "sleep-states" or "suspend-mode".

As the OS has not started yet, the HD indicator lamp should give true
readings, initially, as the system boots.  Only when the system starts
regularly accessing the page-file, should you expect to see any bogus
readings due to your OS.

Making such observations should at least tell you if there is a greater
problem with your machine.

Also, making comparisons with the output of the "Disk Monitor" utility and
your HD activity lamp should give you further clues as to what is

(The URL for Disk Monitor utility is again; )


Cheers,    Tim Meddick,    Peckham, London.    :-)
Jim replied to J. P. Gilliver (John) on 28-Dec-10 06:45 AM
Yes, I have 4 drives in this rack mount machine, and it sounds like it
is actually accessing something.

Jim replied to Twayne on 28-Dec-10 06:48 AM
The laptop has at least 3 times as many processes running as the rack
mount, because the XP PRO on the rack mount is almost a brand new
install of WIndows.  I use it just for video work, and it has a
minimal number of programs installed.

Jim replied to Tim Meddick on 29-Dec-10 03:34 AM

I installed the Disk Monotor and can see no direct correlation between
the light panel light, the DISK MON light, and the log written by the
Disk Mon program, and the activity in Task Manager.  The program is
writing occasionally to 5 of the same sectors on the hard drive (not
sure which drive it is, there are 4 in the machine).  THe same data is
apparently written over and over again, at random intervals, but not
in synch with the log written by DIsk Mon, and they are always WRITEs,
I see no READs.

I'' have to read the HELP files on the program and see if they help.

Tim Meddick replied to Jim on 29-Dec-10 10:12 AM
Not sure why you wrote "not sure which drive it is, there are 4 in the
machine" ? as in the display panel (double-click on the system-try icon) it
clearly states under the column-heading "Disk" which drive is responsible
for that entry (numbered 0 to whatever).

Obviously, whatever drive you have installed your XP installation to (i.e
the SYSTEM drive) is going to be "by far and away" the most active,
normally, any other drives will only put in an appearance once in a very
rare while.

Also, there should be an equal [on average] number of read and write i/o
operations listed in the output [display] window.  But if you find that, as
you seemed to be saying, there is a heavy "bias" toward just "reads" or
just all "write" operations try waiting a while and allowing the system to
three minutes.

*NB The output [display] window does *not* capture any i/o data all the
while it is in "minimized" "Disk Tray Light" - mode.


Cheers,    Tim Meddick,    Peckham, London.    :-)
Twayne replied to Jim on 29-Dec-10 05:50 PM
Ah, that means it could be indexing or backgroun d AV working. You should be
able to find your settings for those and tell whether those or other
programs are workiing in the background. Both are easy to check & turn off,
just to check. If you turn off AV, disconnect from the 'net first.
Since you mentioned video work: those are very disk intensive, especially
when you do renderings. Have you kept that disk defragmented? In my case I
had to defrag after every full session; the fragmentation would be anywhere
from 80% to 100% on the dedicated drive I used for video work. I am not sure
exactly how those relate, but they did in my case.
I started out letting it run in the background but listening to all the
disk accesses all the time bugged me so I switched off the background work
and did it manually. Done after every session it is not that time intensive.
Also, with video work and the gazillions of temporary files it creates,
you may also be indexing those. Turn off the indexing on that drive & see if
that helps.

Sounds like you just have to figure out which program is running in the
background and take care of it. Autoruns is still a good tool for figuring
that out.