xref: /dragonfly/sbin/badsect/badsect.8 (revision 1de703da)
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32.\"     @(#)badsect.8	8.1 (Berkeley) 6/5/93
33.\" $FreeBSD: src/sbin/badsect/badsect.8,v 1.10.2.6 2002/08/21 18:58:06 trhodes Exp $
34.\" $DragonFly: src/sbin/badsect/badsect.8,v 1.2 2003/06/17 04:27:32 dillon Exp $
35.\"
36.Dd June 5, 1993
37.Dt BADSECT 8
38.Os
39.Sh NAME
40.Nm badsect
41.Nd create files to contain bad sectors
42.Sh SYNOPSIS
43.Nm
44.Ar bbdir sector ...
45.Sh DESCRIPTION
46The
47.Nm
48utility makes a file to contain a bad sector.  Normally, bad sectors
49are made inaccessible by the standard formatter, which provides
50a forwarding table for bad sectors to the driver.
51If a driver supports the bad blocking standard it is much preferable to
52use that method to isolate bad blocks, since the bad block forwarding
53makes the pack appear perfect, and such packs can then be copied with
54.Xr dd 1 .
55The technique used by this program is also less general than
56bad block forwarding, as
57.Nm
58can't make amends for
59bad blocks in the i-list of file systems or in swap areas.
60.Pp
61On some disks,
62adding a sector which is suddenly bad to the bad sector table
63currently requires the running of the standard
64.Tn DEC
65formatter.
66Thus to deal with a newly bad block
67or on disks where the drivers
68do not support the bad-blocking standard
69.Nm
70may be used to good effect.
71.Pp
72The
73.Nm
74utility is used on a quiet file system in the following way:
75First mount the file system, and change to its root directory.
76Make a directory
77.Li BAD
78there.
79Run
80.Nm
81giving as argument the
82.Ar BAD
83directory followed by
84all the bad sectors you wish to add.
85(The sector numbers must be relative to the beginning of
86the file system, but this is not hard as the system reports
87relative sector numbers in its console error messages.)
88Then change back to the root directory, unmount the file system
89and run
90.Xr fsck 8
91on the file system.  The bad sectors should show up in two files
92or in the bad sector files and the free list.  Have
93.Xr fsck
94remove files containing the offending bad sectors, but
95.Em do not
96have it remove the
97.Pa BAD/ Ns Em nnnnn
98files.
99This will leave the bad sectors in only the
100.Li BAD
101files.
102.Pp
103The
104.Nm
105utility works by giving the specified sector numbers in a
106.Xr mknod 2
107system call,
108creating an illegal file whose first block address is the block containing
109bad sector and whose name is the bad sector number.
110When it is discovered by
111.Xr fsck 8
112it will ask
113.Dq Li "HOLD BAD BLOCK \&?" .
114A positive response will cause
115.Xr fsck 8
116to convert the inode to a regular file containing the bad block.
117.Sh SEE ALSO
118.Xr fsck 8
119.Sh DIAGNOSTICS
120The
121.Nm
122utility refuses to attach a block that
123resides in a critical area or is out of range of the file system.
124A warning is issued if the block is already in use.
125.Sh BUGS
126If more than one sector which comprise a file system fragment are bad,
127you should specify only one of them to
128.Nm ,
129as the blocks in the bad sector files actually cover all the sectors in a
130file system fragment.
131.Sh HISTORY
132The
133.Nm
134utility appeared in
135.Bx 4.1 .
136