Friday, May 11, 2012
Windows 8 to Better Detect And Fix Hard Disk Problems
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In Windows 8, Microsoft has redesigned the chkdsk
utility - the tool for hard disk corruption detection
and fixing - in an effort to make the diagnostic and
repair process less intrusive and disruptive.
In Windows 8 Microsoft increased the number of issues
that can be handled online and hence reduced any further
need for chkdsk.
Some corruptions are intermittent due to memory issues
and may not be a result of an actual corruption on the
disk; so Microsoft added a new service to Windows 8,
called the spot verification service. It is triggered by
the file system driver and it verifies that there is
actual corruption on the disk before moving the file
system along in the "health model." This new service
runs in the background and does not affect the normal
functioning of the system.
When an issue is verified, this triggers an online scan
of the file system, which runs as a maintenance task in
the file system. In Windows 8, scheduled tasks that are
for the maintenance of the computer run only when
appropriate (during idle time, etc.). This scan can run
as a background task while other programs continue to
run in the foreground. As the file system is scanned,
all issues that are found are logged for later
At the user or administrator's convenience, the volume
can be taken offline, and the corruptions logged in the
previous step can be fixed. The downtime from this
operation, called "Spotfix," takes only seconds, and on
Windows Server 8 systems with cluster shared volumes,
Microsoft's engineers have eliminated this downtime
completely. With this new model, chkdsk offline run time
is now directly proportional to the number of
corruptions, rather than being proportional to the
number of files as in the old model.
Windows 8 now exposes the state of the file system via
the following interfaces:
Action Center - The health of the drive is most visible
in the Action Center as the "Drive Status", which tells
you when you need to take an action to bring the volume
to a healthy state.
Explorer: The health state is also exposed in Explorer,
under Drive properties.
PowerShell: You can also invoke the chkdsk functionality
using a new cmdlet in PowerShell, REPAIR-VOLUME, which
can be helpful for remote management of file system
Server Manager: In Windows Server, you can also manage
the volume health states directly from the server
In the OS's new 'health model', the file system health
status transitions through four states:
Online and healthy
Online spot verification needed
Online scan needed
Spot fix needed
Online and healthy - In this state there are no detected
file system corruptions and there is no action required
Online spot verification needed - The file system stays
in this transient state only for a brief instant after
the file system finds a corruption that it cannot
self-heal; it puts the volume in this state until the
spot verification service verifies the corruption.
Again, there is no user action required.
Online scan needed? When the spot-verification service
confirms the corruption, it puts the file system in the
"online scan needed" state. In the next maintenance
window, an online scan is performed; there is no user
action required. This state is reflected in the Action
Center, so you can run the scan manually if you want to
do that before the next maintenance window. The scan is
run as a background operation. During this online scan,
all verified issues and fixes are logged for later
repair. On Windows Server 8 systems, idle time is
determined by monitoring the CPU and storage idle times.
Spot fix needed? The file system puts the volume in this
state after the online scan is completed, if required,
and this state is reflected in the Action Center. On
client systems, you can restart the PC to fix all the
file system issues logged in the previous step. The
restart is quick (adding just a few additional seconds)
and the PC is returned to a healthy state. For Windows
Server 8 systems, a restart is unnecessary to fix
corruptions on data volumes. Administrators can simply
schedule a spot fix during the next maintenance window.
For more advanced users who want to avoid restarting
their system to fix a non-system volume corruption, they
can open the Properties dialog for the affected volume,
and on the Tools tab, they'll see an option to check the
drive for file system errors. Corruption on drives that
are not currently in use can be fixed without needing a
full restart of the computer.