This article was previously published under Q130839
This article has been archived. It is offered "as is" and will no longer be updated.
An NTFS volume containing a very large number of files may exhibitdegradation in performance when you create new files.
In an effort to provide consistently good performance, the Windows NT filesystem (NTFS) reserves a portion of disk space for use by the file systemitself. In situations where very little disk space is available, Windows NTmay need to release some of this space in order to allocate space for userfiles. In the vast majority of cases, this algorithm works well. In onespecialized case, however, it is possible for the algorithm to actuallydegrade performance by a significant amount.
The worst case occurs if all of the following conditions are true:
NTFS is formatted with a smaller cluster factor than the default.
Less than 1/8th of the total disk space is available.
The volume has never had more files on it at one time than it has now.
The problem described here only occurs when you create new files, and thetotal number of files is being increased to a number greater than everbefore. The magnitude of the performance degradation depends on the historyof file creation on the volume. It is possible to observe degradation withas few as several hundred thousand files. It is also possible to createmore than two million files on a single volume without observingsignificant performance degradation depending on the pattern of filecreation.
To work around this problem, reduce the total number of files on the volumeor reformat the volume. To minimize the impact of the problem when a verylarge number of files is required, attempt to create the smaller filesfirst before most of the disk space is already in use.
Microsoft has confirmed this to be a problem in Windows NT version 3.5. Afix to this problem is in development, but has not been regression-testedand may be destabilizing in production environments. Microsoft does notrecommend implementing this fix at this time. Contact Microsoft ProductSupport Services for more information on the availability of this fix.