[THIN] Re: We shall see
- From: "Jim Kenzig http://thethin.net" <jimkenz@xxxxxxxxxxxxxx>
- To: <thin@xxxxxxxxxxxxx>
- Date: Thu, 5 Jun 2003 22:31:46 -0400
And how to get the dskcache tool which remains a mystery.
JK
http://support.microsoft.com/?kbid=811392
Obtain the Dskcache.exe Tool to Configure the "Power Protected" Write Cache
Option
The information in this article applies to:
Microsoft Windows 2000 Server SP3
Microsoft Windows 2000 Advanced Server SP3
Microsoft Windows 2000 Professional SP3
Microsoft Windows XP Professional
Microsoft Windows XP Home Edition
SUMMARY
This article describes how to obtain the Dskcache.exe tool. Dskcache.exe is
a command-line tool that you can use to configure the Power Protected write
cache option that is available in the hotfix that is described in the
following Microsoft Knowledge Base article:
332023 Slow Disk Performance with Write Caching Enabled
Note You must install the update described in 332023 KB.EN-US and then
restart your computer before you use the Dskcache.exe tool to configure the
Power Protected write cache option.
MORE INFORMATION
Warning If you turn on the Power Protected write cache option for a
write-caching disk drive, you turn off routines that are built in to the
Windows 2000 disk drivers that make sure that critical data is written to
the disk immediately, instead of being written to the disk later from the
disk's built-in write cache. Do not turn on the Power Protected write cache
option unless your computer and any connected hard disks are protected
against accidental or inadvertent power loss through hardware design that
may include such features as redundant battery-backed power supplies or
onboard batteries on caching controllers. Contact the vendors of your
computer and storage devices to determine the degree of protection afforded
by your hardware. Do not turn on the Power Protected write cache option
unless you understand and accept the level of risk that may be involved, and
are confident that this risk has been mitigated through appropriate hardware
power protection.
For additional information about this issue, click the following article
number to view the article in the Microsoft Knowledge Base:
281672 Possible Data Loss After You Enable the "Write Cache Enabled" Feature
A supported feature that modifies the product's default behavior is now
available from Microsoft, but it is only intended to modify the behavior
that is described in this article. Apply it only to systems that
specifically need it. This feature may receive additional testing.
Therefore, if your system is not severely affected by the lack of this
feature, Microsoft recommends that you wait for the next Windows 2000 or
Windows XP service pack that contains this feature.
To obtain this feature immediately, contact Microsoft Product Support
Services. For a complete list of Microsoft Product Support Services phone
numbers and information on support costs, visit the following Microsoft Web
site:
http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS
The English version of this fix has the file attributes (or later) that are
listed in the following table. The dates and times for these files are
listed in coordinated universal time (UTC). When you view the file
information, it is converted to local time. To find the difference between
UTC and local time, use the Time Zone tab in the Date and Time tool in
Control Panel. Date Time Version Size File name
-------------------------------------------------
24-Feb-2003 20:19 1.0.0.0 10,512 Dskcache.exe
Dskcache.exe Usage Information
dskcache [ +p | -p ] [ +w | -w ] [/i | /s | Drive_Specifier ]
Set (+) or clear (-) the disk cache value:
p : Power protected write cache (not supported on all operating system
versions)
w : Write cache
Drive selection (default is all drives)
/i : Integrated device electronics (IDE) disks only
/s : Small computer system interface (SCSI) (includes Fiber Channel) disks
only
Drive_Specifier : Drive letter, volume name, or physical drive. Use the
following formats:
Drive letter in the following format: c:, d:, and others
Volume name in the following format:
\\?\Volume{8fc37c41-bdd3-11d5-b897-806d6172696f}\
Physical drive: PhysicalDrive0, PhysicalDrive1, and others
If no options are used, current settings for all fixed disks will be
displayed.
Notes
Use the w switch to turn on and turn off write caching to improve disk
performance.
Use the p switch to turn on and turn off the Power Protected write cache
option.
If you turn on the Power Protected write cache option, you increase the risk
of data loss or corruption that may occur during a power outage or equipment
failure. Only turn on this option for disk devices that are adequately
protected against accidental loss of power. See the warning at the beginning
of this section.
Note The Power Protected write cache option can only be turned on for disks
that are currently present. Because the Power Protected write cache option
is turned off by default, this option is turned off for any disks that may
be added after you apply this setting. If you add additional disks, you must
turn on the Power Protected write cache option for those added disks for the
setting to take effect.
Dskcache.exe Command Output
If you run Dskcache without any parameters, the current write cache settings
for all hard disks are displayed. For each hard disk currently present on
your computer, the following information is displayed:
Disk device:
Volume name of the form: \\?\Volume{8fc37c41-bdd3-11d5-b897-806d6172696f}\
Current Settings:
Write Cache is [ enabled | disabled ]
Power Protect is [ enabled | disabled ]
If you run Dskcache with the w switch or the p switch, the specified
settings are applied to the specified disks immediately. This behavior
occurs if the disks and their drivers support querying and modifying the
requested configuration options. (See "Common Error Messages" below.)
For each fixed disk that is currently present on your computer, the
following information is displayed:
Disk device:
Volume name of the form: \\?\Volume{8fc37c41-bdd3-11d5-b897-806d6172696f}\
Current Settings:
Write Cache is [ enabled | disabled ]
Power Protect is [ enabled | disabled ]
New Settings:
Write Cache is [ enabled | disabled ]
Power Protect is [ enabled | disabled ]
Common Error Messages
You may receive one of the following error messages:
Error getting Write Cache value.
(50) The write cache is not modifiable.
This error message indicates that the specified disk device (or its driver)
does not report its write cache status through industry-standard mechanisms
(that is, according to the relevant SCSI or ATAPI [IDE] specifications).
Many RAID controllers are included in this category. For these disks, the
write cache is not configurable through any means available from Microsoft;
it is configurable only through mechanisms provided by the hardware vendor.
The Microsoft disk drivers do not enable write caching for such drives. As a
result, the Dskcache tool that is described in this article and the hotfix
that is described in Microsoft Knowledge Base article 332023 KB.EN-US are
not applicable in these cases.
Error getting Write Cache value.
(1117) The request could not be performed because of an I/O device error.
This error message indicates that the disk device does not return
information about its write caching status in response to the appropriate
SCSI or ATAPI command. This error message is simply an indication of the
capabilities (or lack thereof) of the device or its driver, and it typically
implies that either the device does not support write caching or that the
device driver does not support the commands that are required to query and
set the device's write cache setting.
To resolve this issue, contact the vendor of the disk device.
Error getting Power Protect value.
(21) The device is not ready.
This error can have several different causes. If this error occurs on only
one disk, and the disk is part of an external storage array, this message
may indicate that the disk is simply offline. Bring the disk online and
repeat the dskcache command to apply the settings you want to use. If this
error occurs on all disks that are part of a storage array shared by
multiple servers in a cluster, this message typically indicates that you are
running the dskcache command on a server (node) that is not the owner of the
storage array or device.
To apply the Power-Protected write cache setting to all servers in the
cluster, follow these steps:
Install the update from 332023 KB.EN-US on all nodes (servers) in the
cluster, and then restart each server so that the updated drivers will be
loaded.
On each server in turn, make that server (node) the Owner of the disk or
array (using Move Group to move the disk resources to that node), and then
run the dskcache command on that server.
Repeat step 2 as required for each server (node) in the cluster.
Last Reviewed: 4/10/2003
Keywords: kbQFE kbWin2000preSP4Fix kbfix KB811392 kbAudITPRO kbAudEndUser
kbAudDeveloper kbAudOEM
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