Dirty Bits?

J

Joe McGuire

When I rebooted my computer (WinXP SP3) I got a bizarre message saying that
"The volume is dirty," apparently in reference to my external hard drive.
What the $%^& does this mean? And more particularly, must I do something
about whatever is "dirty" about that drive? When I did a google search I
found a reference to "setting the dirty bit," terminology which, I must
admit, seems to have more to do with connubial delights than with my
computer. of course, I also found ads hawking software which assuredly
(yeah, sure) would fix this and any other problems I might have.
 
J

John John - MVP

Joe said:
When I rebooted my computer (WinXP SP3) I got a bizarre message saying that
"The volume is dirty," apparently in reference to my external hard drive.
What the $%^& does this mean? And more particularly, must I do something
about whatever is "dirty" about that drive? When I did a google search I
found a reference to "setting the dirty bit," terminology which, I must
admit, seems to have more to do with connubial delights than with my
computer. of course, I also found ads hawking software which assuredly
(yeah, sure) would fix this and any other problems I might have.

Run a chkdsk on the drive in question.

John
 
J

Jose

When I rebooted my computer (WinXP SP3) I got a bizarre message saying that
"The volume is dirty," apparently in reference to my external hard drive.
What the $%^& does this mean?  And more particularly, must I do something
about whatever is "dirty" about that drive?  When I did a google searchI
found a reference to "setting the dirty bit," terminology which, I must
admit, seems to have more to do with connubial delights than with my
computer.  of course, I also found ads hawking software which assuredly
(yeah, sure) would fix this and any other problems I might have.

It is not so bizarre. It is XP doing it's job.

When XP starts, it checks to see if any volumes have the dirty bit set
and if they do, it will run chkdsk on them to try to clear up the
problem. The dirty bit can be set manually, it may have been as a
consequence of a power interruption, or something set it for you.

The best thing to do is let XP run the chkdsk when your system
restarts and clear the dirty bit for you.

You cannot clear the dirty bit manually and you should not want to.
It means there is a problem somewhere and you need to fix it.

You can query the dirty bit on any volume from a command prompt.

To query the dirty bit on drive C, type:

fsutil dirty query C:

Sample output:
Volume C: is dirty
Volume C: is not dirty

You can set the dirty bit on any volume to force a chkdsk on the next
reboot.

To set the dirty bit on drive C, type:

fsutil dirty set C:

If your system continues to exhibit this behavior you have another
problem. If the dirty bit will never clear because of a hardware
problem, you can tell XP not to run chkdsk on the volume when it
restarts and it will stay dirty. That is up to you but I would not
recommend it.

When chkdsk runs automatically on a reboot, the results are shown in
the Event Viewer Application log.

To see the Event Viewer logs, click Start, Settings, Control Panel,
Administrative Tools, Event Viewer.

A shortcut to Event Viewer is to click Start, Run and in the box
enter:

%SystemRoot%\system32\eventvwr.msc

Click OK to launch the Event Viewer.

Look in the Application log for an event sourced by Winlogon,
something like:

Event Type: Information
Event Source: Winlogon
Event Category: None
Event ID: 1001
Description:
Checking file system on C:
The type of the file system is NTFS.


A disk check has been scheduled.
Windows will now check the disk.

CHKDSK is verifying Usn Journal...
Usn Journal verification completed.

39070048 KB total disk space.
25151976 KB in 78653 files.
48256 KB in 10264 indexes.
0 KB in bad sectors.
237080 KB in use by the system.
65536 KB occupied by the log file.
13632736 KB available on disk.

4096 bytes in each allocation unit.
9767512 total allocation units on disk.
3408184 allocation units available on disk.

Windows has finished checking your disk.
Please wait while your computer restarts.
 
T

Tim Slattery

Joe McGuire said:
When I rebooted my computer (WinXP SP3) I got a bizarre message saying that
"The volume is dirty," apparently in reference to my external hard drive.
What the $%^& does this mean?

All it means is that your last shutdown didn't go quite as planned.
"Dirty" just means that a change has been made to the drive, and it
hasn't been completed. In a normal shutdown, all i/o would be
completed before the machine turned itself off.

I'm more familiar with the term in the context of an application. You
open a document in some app, then edit it. When you make a change, the
document becomes "dirty". When you save it, it's clean again. When you
close the app it checks the "dirty" bit. If it's set it asks you
whether you want to save your changes.

In this case, it would be a good idea to run chkdsk.
 
J

Joe McGuire

Thanks to you and others who responded. I had to force a shutdown just
before I got this message and your explanation clarifies what probably
happened.
 

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