dos filesystem components checked by fsck
The following two components are checked:
File Allocation Table (FAT)
dosfs-fsck phase 1: check FATs
Every dos filesystem maintains two or more identical copies of the
File Allocation Table (FAT).
During Phase 1, fsck performs two types of checks:
The FATs are checked first for readability.
At least one FAT must be readable for fsck to proceed.
All readable FATs are checked to see if they are in sync.
If FATs are in sync,
Phase 2 occurs.
dosfs-fsck phase 2: check directory entries (pass 1)
During Phase 2, fsck performs the following checking:
The following information is collected during Phase 2:
If the entry is for ``..'', check that the start cluster
matches the one for the parent directory.
If the entry is for ``.'', check that the start cluster
matches the one for the current directory.
If the entry is for a directory, check that file size is zero.
If the entry is for a file, check that the file size is set
to the correct byte count.
For each directory entry check that:
its start cluster number is within range
all its FAT entries are within range
If the entry is for a long name, then check the
Also check for the presence of an associated alias
number of subdirectories
number of regular files
number of hidden files
byte count per subdirectories
byte count per regular files
byte count per hidden files
for each cluster in the filesystem, number of times it is
being claimed. This information is used during cross referencing checking.
dosfs-fsck phase 3: cross reference check
During Phase 3, fsck will perform the following checking:
allocation units (clusters) claimed by more than one directory entry
lost clusters (clusters not claimed by any directory entry
but still marked FREE in the FAT)
dosfs-fsck phase 4: check directory entries (pass 2)
Phase 4 is the same as Phase 2. It is only needed and performed by fsck
if there was a corrective action performed during cross-referencing checking
that had invalidated the data collected during Phase 2.
dosfs-fsck phase 4: check boot area (FAT 32 only)
Check location of backup boot sector.
Check location and contents of FS info sector.
© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 22 April 2004