Performing Direct Disk Writes

Previously reserved fields in the file system directory entry are used for storing the last access date and the creation date and time. A file with a long filename, which is longer than 5 characters, will also cause the system to use previously reserved fields in the directory entry. In previous versions of MS-DOS and Windows, these reserved entries were zero. Older disk repair and checking utilities that have not been updated for Windows 95 might display errors about the disk because of the usage of these reserved entries. It is possible that an older disk repair utility could either destroy the long filename or the actual data in a file because it would mistakenly interpret the file as corrupted. For this reason, Windows 95 won't support old utilities that perform direct disk writes. A newer version of the utility that understands the newer on-disk file system structures will obtain an exclusive volume lock and proceed correctly. This feature is called exclusive volume locking.

Exclusive volume locking is also needed because the system is a multitasking system and disk utilities need exclusive access so that they can modify the file system without causing the file system to be inconsistent for the other executing applications.