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c04656a2 KM |
1 | .\" Copyright (c) 1980 Regents of the University of California. |
2 | .\" All rights reserved. The Berkeley software License Agreement | |
3 | .\" specifies the terms and conditions for redistribution. | |
4 | .\" | |
7391377d | 5 | .\" @(#)bad144.8 6.3 (Berkeley) %G% |
c04656a2 | 6 | .\" |
e4365bad | 7 | .TH BAD144 8 "" |
c04656a2 KM |
8 | .UC 4 |
9 | .SH NAME | |
10 | bad144 \- read/write dec standard 144 bad sector information | |
11 | .SH SYNOPSIS | |
79d6ffc9 KM |
12 | .B /etc/bad144 |
13 | [ | |
14 | .B \-f | |
51d860e6 MK |
15 | ] [ |
16 | .B \-c | |
17 | ] [ | |
18 | .B \-v | |
79d6ffc9 | 19 | ] |
c04656a2 KM |
20 | disktype disk |
21 | [ sno [ | |
22 | bad ... | |
23 | ] ] | |
51d860e6 MK |
24 | .br |
25 | .B /etc/bad144 | |
26 | .B \-a | |
27 | [ | |
28 | .B \-f | |
29 | ] [ | |
30 | .B \-c | |
31 | ] [ | |
32 | .B \-v | |
33 | ] | |
34 | disktype disk | |
35 | [ | |
36 | bad ... | |
37 | ] | |
c04656a2 KM |
38 | .SH DESCRIPTION |
39 | .I Bad144 | |
40 | can be used to inspect the information stored on a disk that is used by | |
41 | the disk drivers to implement bad sector forwarding. The format of | |
42 | the information is specified by DEC standard 144, as follows. | |
43 | .PP | |
44 | The bad sector information is located in the first 5 even numbered sectors | |
45 | of the last track of the disk pack. There are five identical copies of | |
79d6ffc9 KM |
46 | the information, described by the |
47 | .I dkbad | |
48 | structure. | |
c04656a2 KM |
49 | .PP |
50 | Replacement sectors are allocated starting with the first sector before | |
51 | the bad sector information and working backwards towards the beginning | |
52 | of the disk. A maximum of 126 bad sectors are supported. The position | |
51d860e6 MK |
53 | of the bad sector in the bad sector table determines the replacement |
54 | sector to which it corresponds. | |
79d6ffc9 | 55 | The bad sectors must be listed in ascending order. |
c04656a2 KM |
56 | .PP |
57 | The bad sector information and replacement sectors are conventionally | |
79d6ffc9 | 58 | only accessible through the ``c'' file system partition of the disk. If |
c04656a2 KM |
59 | that partition is used for a file system, the user is responsible for |
60 | making sure that it does not overlap the bad sector information or any | |
61 | replacement sectors. | |
51d860e6 MK |
62 | Thus, one track plus 126 sectors must be reserved to allow use |
63 | of all of the possible bad sector replacements. | |
c04656a2 KM |
64 | .PP |
65 | The bad sector structure is as follows: | |
66 | .PP | |
67 | .ta .75i 1.5i 3.5i | |
68 | .nf | |
69 | struct dkbad { | |
70 | long bt_csn; /* cartridge serial number */ | |
71 | u_short bt_mbz; /* unused; should be 0 */ | |
72 | u_short bt_flag; /* -1 => alignment cartridge */ | |
73 | struct bt_bad { | |
74 | u_short bt_cyl; /* cylinder number of bad sector */ | |
75 | u_short bt_trksec; /* track and sector number */ | |
76 | } bt_bad[126]; | |
77 | }; | |
78 | .fi | |
79 | .PP | |
79d6ffc9 KM |
80 | Unused slots in the |
81 | .I bt_bad | |
82 | array are filled with all bits set, a putatively | |
c04656a2 KM |
83 | illegal value. |
84 | .PP | |
85 | .I Bad144 | |
86 | is invoked by giving a device type (e.g. rk07, rm03, rm05, etc.), and a device | |
51d860e6 MK |
87 | name (e.g. hk0, hp1, etc.). With no optional arguments |
88 | it reads the first sector of the last track | |
c04656a2 | 89 | of the corresponding disk and prints out the bad sector information. |
51d860e6 MK |
90 | It issues a warning if the bad sectors are out of order. |
91 | .I Bad144 | |
92 | may also be invoked with a serial number for the pack and a list | |
93 | of bad sectors. | |
94 | It will write the supplied information into all copies | |
95 | of the bad-sector file, replacing any previous information. | |
96 | Note, however, that | |
c04656a2 KM |
97 | .I bad144 |
98 | does not arrange for the specified sectors to be marked bad in this case. | |
51d860e6 | 99 | This procedure should only be used to restore known bad sector information which |
c04656a2 | 100 | was destroyed. |
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101 | It is necessary to reboot before any change will take effect. |
102 | .PP | |
103 | With the | |
104 | .B \-a | |
105 | option, | |
106 | the argument list consists of new bad sectors to be added to an existing | |
107 | list. | |
108 | The new sectors are sorted into the list, | |
109 | which must have been in order. | |
110 | Replacement sectors are moved to accommodate the additions; | |
111 | the new replacement sectors are cleared. | |
112 | The entire process is described as it happens in gory detail if | |
113 | .B \-v | |
114 | (verbose) is given. | |
115 | The | |
116 | .B \-c | |
117 | option forces an attempt to copy the old sector to the replacement, | |
118 | and may be useful when replacing an unreliable sector. | |
c04656a2 | 119 | .PP |
51d860e6 MK |
120 | If the disk is an RP06, RM03, RM05, Fujitsu Eagle, |
121 | or SMD disk on a Massbus, the | |
79d6ffc9 | 122 | .B \-f |
7391377d MK |
123 | option may be used to mark the new bad sectors as ``bad'' |
124 | by reformatting them as unusable sectors. | |
51d860e6 | 125 | \fBNOTE: this can be done safely only when there is no other disk activity\fP, |
79d6ffc9 | 126 | preferably while running single-user. |
7391377d MK |
127 | This option is required unless the sectors have already been marked bad, |
128 | or the system will not be notified that it should use the replacement sector. | |
c04656a2 | 129 | .SH SEE ALSO |
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130 | badsect(8), |
131 | format(8V) | |
c04656a2 | 132 | .SH BUGS |
79d6ffc9 | 133 | It should be possible to format disks on-line under UNIX. |
c04656a2 | 134 | .PP |
79d6ffc9 KM |
135 | It should be possible to mark bad sectors on drives of all type. |
136 | .PP | |
137 | On an 11/750, | |
138 | the standard bootstrap drivers used to boot the system do | |
139 | not understand bad sectors, | |
51d860e6 | 140 | handle ECC errors, or the special SSE (skip sector) errors of RM80-type disks. |
c04656a2 | 141 | This means that none of these errors can occur when reading the file |
79d6ffc9 KM |
142 | /vmunix to boot. Sectors 0-15 of the disk drive |
143 | must also not have any of these errors. | |
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144 | .PP |
145 | The drivers which write a system core image on disk after a crash do not | |
146 | handle errors; thus the crash dump area must be free of errors and bad | |
147 | sectors. |