disk caching

24-03-2005

Hello

For testing purposes, I enabled "Enable write caching on
the disk" in a Windows Server 2003 DC, from Disk
Properties > Hardware tab > Properties > Plicies tab.

When I restarted the machine, the change goes back to the
previous settings, i.e. disabled. Is there any registry
key to modify so that write caching remains enabled ? Or
any other method ...

I tried the same test on a standalone Windows Server
2003, I did not have any problem.

Many thanks

Best

Jason Tan · 25-03-2005

Hi

Thanks for posting!

I understand that you cannot preserve the check for "Enable write caching
on the disk". If I have misunderstood your concerns, please feel free to
let me know.

Based on my research, it could be the cause that some third-party queries
and does not permit change the option when restart the machine. Therefore,
if possible, I suggest you perform a clean boot on non-business time and
test if the issue still persists.

===========================
1. Click the "Start" and select "Run".
2. Type msconfig in the open box, and then click "OK".
3. On the "Services" tab, click to choose "Hide All Microsoft Services" and
click to choose Disable All.
4. On the Startup page, click Disable All.
5. Click "OK" to reboot your computer.
6. When you see the message, choose "Don't show this message or launch the
System Configuration Utility when Windows starts" and click OK.

The below article can also be applied to Windows 2003
310353 How to perform a clean boot in Windows XP
http://support.microsoft.com/?id=310353

This option could be related to the following registry key which I traced
on my system by Regmon tool. Please check the corresponding registry key of
your machine. I suspect that when starting the machine the option will be
revised back by some third party.

HKLM\System\CurrentControlSet\Enum\IDE\DiskMaxtor_33073H3___________________
_______YAH814Y0\334c414a38304354202020202020202020202020\Device
Parameters\Disk\UserWriteCacheSetting

More information for your reference:
Regmon download
http://www.sysinternals.com/ntw2k/source/regmon.shtml

I look forward to your response. If there is anything that is unclear,
please feel free to let me know.

Thanks & Regards,

Jason Tan

Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security

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25-03-2005

Thank you Jason

Please can I just ask you:

Have you tested it on 2003 Domain Controller (and not
standalone) with IDE Disk Maxtor ? For some reasons I
assumed that it could be because it is a DC which has not
write cache on disk.

The Disk on which I am trying to enable "Enable write
caching on the disk" with no success, is IDE Western
Digital.

Jason Tan · 29-03-2005

Hi

Thanks for your reply!

Please excuse me that I have tested the issue on a standalone Windows
Server 2003 other than a DC in the first place since I neglect it could be
related to DC. To verify your concerns, I test it again on a Windows 2003
Domain Controller on my side. The issue can be reproduced. Based on my
further research, I would like to provide you with the following
information.

CAUSE
=========
By default, write caching is disabled on a disk that contains the Active
Directory database (Ntds.dit). Also, write caching is disabled on a disk
that contains the
Active Directory log files. By doing this, you enhance the reliability of
the Active Direcory files.

Move the Active Directory database and the Active Directory log files off
of a disk in which you need to enable write caching. For more information,
see the following article:

257420 HOW TO: Move the Ntds.dit File or Log Files
http://support.microsoft.com/?id=257420

WORKAROUND
===================
There is a workaround to force on write caching for all drives when the
computer is started. It involves using the Dskcache.exe tool from the
following article in a startup script:

811392 Obtain the Dskcache.exe Tool to Configure the "Power Protected" Write
http://support.microsoft.com/?id=811392

Please note that enabling write cache for drives that contain the active
directory database or logs is not recommended since data loss can occur.
However, here are the steps:

1. Download Dskcache.exe from 811392 and copy it to the root of C:

2. Create a .CMD called EnableCache.CMD on the root of C:\ that contains
the following text:

echo off
c:\dskcache.exe +w
exit

3. Click Start, click Run, type "gpedit.msc" (without the quotation
marks), and then press ENTER.

4. Browse to the following:

Local Computer Policy\Computer Configuration\Windows Settings\Scripts

5. Double-click Startup and then click Add.

6. Type the following in the Script Name box and click OK:

C:\EnableCache.CMD

7. Click OK and close the Group Policy Object Editor window.

Now each time the computer is restarted, EnableCache.CMD runs to enable
write cache for all disks.

I hope my information helps. If there is anything that is unclear, please
feel free to let me know.

Thanks & Regards,

Jason Tan

Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security

=====================================================

When responding to posts, please "Reply to Group" via your newsreader so
that others may learn and benefit from your issue.

=====================================================
This posting is provided "AS IS" with no warranties, and confers no rights.

01-04-2005

It worked !!!

Is this an excellent or brilliant or fan-ta-stic reply
Jason ? you choose !

Many many thanks !!!

Jason Tan · 01-04-2005

Hi,

I appreciate your update. I am glad to hear that the problem has been fixed
and you are happy. If you have any other questions or concerns, please do
not hesitate to let me know. It is always my pleasure to be of assistance.

Thanks & Regards,

Jason Tan

Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security

=====================================================

When responding to posts, please "Reply to Group" via your newsreader so
that others may learn and benefit from your issue.

=====================================================
This posting is provided "AS IS" with no warranties, and confers no rights.