Windows Runs Slowly Performing Large Backup Operation

ID: Q224073

The information in this article applies to:

SYMPTOMS

While you are backing up a very large number of files to a tape drive or other large-capacity device, or you are comparing an existing backup set to the original files on the hard disk, Windows may begin to run slowly.

This problem is confirmed to occur when you back up a large number of files (2,000-3,000 or more files) if the backup software is configured to perform a comparison between the backed-up files on the tape drive and the original files on the hard disk after the files are backed up. This problem may also occur when you are comparing a set of files that was backed up previously.


CAUSE

This behavior is caused by an error in the Windows 98 protected-mode disk cache (Vcache.vxd). The error occurs when the maximum value of a variable used in tracking the age of blocks in the cache is exceeded. If this occurs while the protected-mode disk cache is attempting to free the oldest blocks to make room for new data, it takes a long time for the operation to finish. Once this condition occurs, Windows runs slowly, and continues to do so until the computer is restarted.


RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp
The English version of this fix should have the following file attributes or later: 

   Date     Time      Version     Size     File name     Platform
   --------------------------------------------------------------
   4/7/99   12:07pm   4.10.2183   37,183   Vcache.vxd    Win98

NOTE: If this product was already installed on your computer when you purchased it from the Original Equipment Manufacturer (OEM) and you need this fix, please call the Pay Per Incident number listed on the above Web site. If you contact Microsoft to obtain this fix, and if it is determined that you only require the fix you requested, no fee will be charged. However, if you request additional technical support, and if your no-charge technical support period has expired, or if you are not eligible for standard no-charge technical support, you may be charged a non-refundable fee.

For more information about eligibility for no-charge technical support, see the following article in the Microsoft Knowledge Base:
Q154871 Determining If You Are Eligible for No-Charge Technical Support


STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.


MORE INFORMATION

This problem has been reported to occur with the following third-party products:

However, this problem is not caused by these products, and could also occur with other high-capacity tape backup hardware and backup software.

Additional query words: very crawl delay hang 


Keywords          : kbenv kbhw 
Version           : WINDOWS:
Platform          : WINDOWS 
Issue type        : kbprb

Last Reviewed: July 2, 1999