xref: /netbsd-src/sbin/badsect/badsect.8 (revision ae1bfcddc410612bc8c58b807e1830becb69a24c)
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32.\"     from: @(#)badsect.8	6.4 (Berkeley) 3/16/91
33.\"	$Id: badsect.8,v 1.4 1993/08/01 07:39:41 mycroft Exp $
34.\"
35.Dd March 16, 1991
36.Dt BADSECT 8
37.Os BSD 4
38.Sh NAME
39.Nm badsect
40.Nd create files to contain bad sectors
41.Sh SYNOPSIS
42.Nm /etc/badsect
43.Ar bbdir sector ...
44.Sh DESCRIPTION
45.Nm Badsect
46makes a file to contain a bad sector.  Normally, bad sectors
47are made inaccessible by the standard formatter, which provides
48a forwarding table for bad sectors to the driver; see
49.Xr bad144 8
50for details.
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 badsect
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 badsect
70may be used to good effect.
71.Pp
72.Nm Badsect
73is used on a quiet file system in the following way:
74First mount the file system, and change to its root directory.
75Make a directory
76.Li BAD
77there.  Run
78.Nm badsect
79giving as argument the
80.Ar BAD
81directory followed by
82all the bad sectors you wish to add.
83(The sector numbers must be relative to the beginning of
84the file system, but this is not hard as the system reports
85relative sector numbers in its console error messages.)
86Then change back to the root directory, unmount the file system
87and run
88.Xr fsck 8
89on the file system.  The bad sectors should show up in two files
90or in the bad sector files and the free list.  Have
91.Xr fsck
92remove files containing the offending bad sectors, but
93.Em do not
94have it remove the
95.Pa BAD/ Ns Em nnnnn
96files.
97This will leave the bad sectors in only the
98.Li BAD
99files.
100.Pp
101.Nm Badsect
102works by giving the specified sector numbers in a
103.Xr mknod 2
104system call,
105creating an illegal file whose first block address is the block containing
106bad sector and whose name is the bad sector number.
107When it is discovered by
108.Xr fsck
109it will ask
110.Dq Li "HOLD BAD BLOCK ?"
111A positive response will cause
112.Xr fsck
113to convert the inode to a regular file containing the bad block.
114.Sh SEE ALSO
115.Xr bad144 8 ,
116.Xr fsck 8 ,
117.Xr format 8
118.Sh DIAGNOSTICS
119.Nm Badsect
120refuses to attach a block that
121resides in a critical area or is out of range of the file system.
122A warning is issued if the block is already in use.
123.Sh BUGS
124If more than one sector which comprise a file system fragment are bad,
125you should specify only one of them to
126.Nm badsect ,
127as the blocks in the bad sector files actually cover all the sectors in a
128file system fragment.
129.Sh HISTORY
130The
131.Nm
132command appeared in
133.Bx 4.1 .
134