Ntbackup Causes Cache to Grow During Restore
Article ID: 164261
Article Last Modified on 11/1/2006
APPLIES TO
- Microsoft Windows NT Workstation 4.0 Developer Edition
- Microsoft Windows NT Server 4.0 Standard Edition
This article was previously published under Q164261
SYMPTOMS
When you run a restore of a big file with the Windows NT Backup tool you
may see that the performance of the user interface and applications
suffers. This happens in both the Restore and the Verify phase. You will
see the problem with files bigger than physical memory.
When you take a look at this in Performance Monitor, you will find that
the cache is very large (from 50 percent to 90 percent of physical memory)
and the process working sets have shrunk.
MORE INFORMATION
The CreateFile API has a flag, FILE_FLAG_SEQUENTIAL_SCAN, that is
especially useful when copying files. It tells Cache Manager not to try to
increase the file cache when requests for this handle arrive. Hence,
Memory Manager does not have to shrink the applications working set to
accommodate the bigger cache.
Although Windows NT Backup uses this flag during Backup, it does not do so
in the Restore phase.
STATUS
Microsoft has confirmed this to be a problem in Windows NT version 4.0.
This problem was corrected in the latest Microsoft Windows NT 4.0 U.S.
Service Pack. For information on obtaining the service pack, query on the
following word in the Microsoft Knowledge Base (without the spaces):
Keywords: kbbug kbfix KB164261