187 lines
6.3 KiB
Groff
187 lines
6.3 KiB
Groff
.\" Copyright (c) 1980, 1988, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)bad144.8 8.1 (Berkeley) 6/6/93
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.\"
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.Dd June 6, 1993
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.Dt BAD144 8
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.Os BSD 4
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.Sh NAME
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.Nm bad144
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.Nd read/write dec standard 144 bad sector information
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.Sh SYNOPSIS
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.Nm bad144
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.Op Fl c
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.Op Fl f
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.Op Fl v
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.Ar disk
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.Oo
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.Ar sno
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.Op Ar bad ...
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.Oc
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.Nm bad144
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.Fl a
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.Op Fl c
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.Op Fl f
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.Op Fl v
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.Ar disk
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.Op Ar bad ...
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.Sh DESCRIPTION
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.Nm Bad144
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can be used to inspect the information stored on a disk that is used by
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the disk drivers to implement bad sector forwarding.
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.Pp
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Available options:
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.Pp
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.Bl -tag -width Ds
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.It Fl a
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The argument list consists of new bad sectors to be added to an existing
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list.
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The new sectors are sorted into the list,
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which must have been in order.
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Replacement sectors are moved to accommodate the additions;
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the new replacement sectors are cleared.
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.It Fl c
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Forces an attempt to copy the old sector to the replacement,
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and may be useful when replacing an unreliable sector.
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.It Fl f
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For a RP06, RM03, RM05, Fujitsu Eagle,
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or
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.Tn SMD
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disk on a Massbus, the
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.Fl f
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option may be used to mark the new bad sectors as ``bad''
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by reformatting them as unusable sectors.
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This option is
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.Em required unless
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the sectors have already been marked bad,
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or the system will not be notified that it should use the replacement sector.
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This option may be used while running multiuser; it is no longer necessary
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to perform format operations while running single-user.
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.It Fl v
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The entire process is described as it happens in gory detail if
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.Fl v
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(verbose) is given.
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.El
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.Pp
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The format of
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the information is specified by
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.Tn DEC
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standard 144, as follows.
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The bad sector information is located in the first 5 even numbered sectors
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of the last track of the disk pack. There are five identical copies of
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the information, described by the
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.Ar dkbad
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structure.
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.Pp
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Replacement sectors are allocated starting with the first sector before
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the bad sector information and working backwards towards the beginning
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of the disk. A maximum of 126 bad sectors are supported. The position
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of the bad sector in the bad sector table determines the replacement
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sector to which it corresponds.
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The bad sectors must be listed in ascending order.
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.Pp
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The bad sector information and replacement sectors are conventionally
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only accessible through the ``c'' file system partition of the disk. If
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that partition is used for a file system, the user is responsible for
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making sure that it does not overlap the bad sector information or any
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replacement sectors.
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Thus, one track plus 126 sectors must be reserved to allow use
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of all of the possible bad sector replacements.
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.Pp
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The bad sector structure is as follows:
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.Bd -literal
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struct dkbad {
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long bt_csn; /* cartridge serial number */
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u_short bt_mbz; /* unused; should be 0 */
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u_short bt_flag; /* -1 => alignment cartridge */
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struct bt_bad {
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u_short bt_cyl; /* bad sector cylinder number */
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u_short bt_trksec; /* track and sector number */
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} bt_bad[126];
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};
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.Ed
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.Pp
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Unused slots in the
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.Ar bt_bad
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array are filled with all bits set, a putatively
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illegal value.
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.Pp
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.Nm Bad144
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is invoked by giving a device name (e.g. hk0, hp1, etc.).
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With no optional arguments
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it reads the first sector of the last track
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of the corresponding disk and prints out the bad sector information.
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It issues a warning if the bad sectors are out of order.
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.Nm Bad144
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may also be invoked with a serial number for the pack and a list
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of bad sectors.
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It will write the supplied information into all copies
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of the bad-sector file, replacing any previous information.
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Note, however, that
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.Nm bad144
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does not arrange for the specified sectors to be marked bad in this case.
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This procedure should only be used to restore known bad sector information which
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was destroyed.
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.Pp
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It is no longer necessary to reboot to allow the kernel
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to reread the bad-sector table from the drive.
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.Sh SEE ALSO
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.Xr badsect 8 ,
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.Xr format 8
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.Sh BUGS
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It should be possible to format disks on-line under
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.Tn UNIX .
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.Pp
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It should be possible to mark bad sectors on drives of all type.
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.Pp
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On an 11/750,
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the standard bootstrap drivers used to boot the system do
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not understand bad sectors,
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handle
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.Tn ECC
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errors, or the special
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.Tn SSE
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(skip sector) errors of RM80-type disks.
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This means that none of these errors can occur when reading the file
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.Pa /kernel
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to boot. Sectors 0-15 of the disk drive
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must also not have any of these errors.
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.Pp
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The drivers which write a system core image on disk after a crash do not
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handle errors; thus the crash dump area must be free of errors and bad
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sectors.
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.Sh HISTORY
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The
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.Nm
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command appeared in
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.Bx 4.1 .
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