You are copying large files (of 50 MB or more) from a computer running
Windows 95 to a computer running Windows NT installed. You are moving the
files with a drag-and-drop operation, using the Network Neighborhood tool
or the My Computer tool in Windows 95. Windows NT CPU use increases to 100
percent, resulting in performance degradation and client disconnections.
The Network Neighborhood and My Computer tools in Windows 95 issue an
SMBwrite of zero bytes at a file's new end-of-file (EOF) offset before
actually writing data to the file. On large file systems that are highly
fragmented, copying a large file can cause the Windows NT file system
(NTFS) to use 100 percent of the CPU for an extended period of time. This
can result in other threads being starved of CPU time, causing performance
degradation and client disconnections.
This problem exists whenever a write of zero bytes occurs at a large offset
beyond EOF on a highly fragmented file system as NTFS tries to allocate
space to satisfy the request.
Using COPY/XCOPY from the DOS-PROMPT or copying to a FAT partition does not
result in this behavior.
Microsoft has confirmed this to be a problem in Windows NT versions 3.5,
3.51 and 4.0. We are researching this problem and will post new
information here in the Microsoft Knowledge Base as it becomes available.