Does anyone know of how to reset the "dirty bit" on a drive. My computer
has 4 hard drives attached and the dirty bit got set on the first two
drives and won't reset. Every time I reboot, it does the disk check on the
drives and then just sits at the restart message. If I hit the reset
button, then it just checks the drive on the restart again. I can't get a
defragger too work as it comes up with the dirty bit message and I'm just
about at my wits end. Any ideas???
Several. Firstly: Be careful what you wish for!
If XP works the way Win9x does in this respect, then there
are two "dirty bits" that flag different situations.
One is set when file writes are in progress, and cleared
when these complete. If the Windows session crashes or
is reset during file write operations, then the bit remains
set and the next startup will cause ChkDsk to test that
volume for file system logic errors, and "fix" them. The
bit is thren cleared once the file system is "fixed".
The other bit is set whenever a disk access fails at the
physical level. This is a far more ominous state of affairs
that can arise at any time; it's not related to "bad exits"
from Windows, but impending hard drive failure. When this
bit is set, ChkDsk will test logic and surface of all volumes
on that physical hard drive - a very long process. It will
"fix" surface errors by marking the bad clusters as not for
use, but that's just papering over the cracks.
These "dirty" bits are not just set for fun - when they are
set, it's because a data loss situation has arisen. For
example, if your system powers off too soon on shutdown so
that data written to HD's on-board RAM has not been flushed
to disk, then that is a data loss situation that will set
the flag, even if Windows considers it a successful shutdown.
Bottom line: Believe the "dirty bit" flag, not Windows UI.
You mention that the system "hangs" when it tries to repair
the damage, or <shudder> when you defrag. This is suggestive
of a failing hard drive, where the low-level driver code gets
trapped in a retry loop (repeatedly trying to read a bad sector,
when bad CRC causes the access to be considered "failed").
If there are any doubts about file system sanity or hard drive
health, do NOT attempt a defrag!! Consider Defrag a way to
make a healthy PC run faster, just as running a marathon is a
way to make a healthy human fitter. You should not try defrag
on a sick PC for the same reason that patients recovering from
a recent heart attack should not run marathons.
)