1.\" Copyright (c) 1980, 1988, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)bad144.8 8.1 (Berkeley) 06/06/93 7.\" 8.Dd 9.Dt BAD144 8 10.Os BSD 4 11.Sh NAME 12.Nm bad144 13.Nd read/write dec standard 144 bad sector information 14.Sh SYNOPSIS 15.Nm bad144 16.Op Fl c 17.Op Fl f 18.Op Fl v 19.Ar disk 20.Oo 21.Ar sno 22.Op Ar bad ... 23.Oc 24.Nm bad144 25.Fl a 26.Op Fl c 27.Op Fl f 28.Op Fl v 29.Ar disk 30.Op Ar bad ... 31.Sh DESCRIPTION 32.Nm Bad144 33can be used to inspect the information stored on a disk that is used by 34the disk drivers to implement bad sector forwarding. 35.Pp 36Available options: 37.Pp 38.Bl -tag -width Ds 39.It Fl a 40The argument list consists of new bad sectors to be added to an existing 41list. 42The new sectors are sorted into the list, 43which must have been in order. 44Replacement sectors are moved to accommodate the additions; 45the new replacement sectors are cleared. 46.It Fl c 47Forces an attempt to copy the old sector to the replacement, 48and may be useful when replacing an unreliable sector. 49.It Fl f 50For a RP06, RM03, RM05, Fujitsu Eagle, 51or 52.Tn SMD 53disk on a Massbus, the 54.Fl f 55option may be used to mark the new bad sectors as ``bad'' 56by reformatting them as unusable sectors. 57This option is 58.Em required unless 59the sectors have already been marked bad, 60or the system will not be notified that it should use the replacement sector. 61This option may be used while running multiuser; it is no longer necessary 62to perform format operations while running single-user. 63.It Fl v 64The entire process is described as it happens in gory detail if 65.Fl v 66(verbose) is given. 67.El 68.Pp 69The format of 70the information is specified by 71.Tn DEC 72standard 144, as follows. 73The bad sector information is located in the first 5 even numbered sectors 74of the last track of the disk pack. There are five identical copies of 75the information, described by the 76.Ar dkbad 77structure. 78.Pp 79Replacement sectors are allocated starting with the first sector before 80the bad sector information and working backwards towards the beginning 81of the disk. A maximum of 126 bad sectors are supported. The position 82of the bad sector in the bad sector table determines the replacement 83sector to which it corresponds. 84The bad sectors must be listed in ascending order. 85.Pp 86The bad sector information and replacement sectors are conventionally 87only accessible through the ``c'' file system partition of the disk. If 88that partition is used for a file system, the user is responsible for 89making sure that it does not overlap the bad sector information or any 90replacement sectors. 91Thus, one track plus 126 sectors must be reserved to allow use 92of all of the possible bad sector replacements. 93.Pp 94The bad sector structure is as follows: 95.Bd -literal 96struct dkbad { 97 long bt_csn; /* cartridge serial number */ 98 u_short bt_mbz; /* unused; should be 0 */ 99 u_short bt_flag; /* -1 => alignment cartridge */ 100 struct bt_bad { 101 u_short bt_cyl; /* bad sector cylinder number */ 102 u_short bt_trksec; /* track and sector number */ 103 } bt_bad[126]; 104}; 105.Ed 106.Pp 107Unused slots in the 108.Ar bt_bad 109array are filled with all bits set, a putatively 110illegal value. 111.Pp 112.Nm Bad144 113is invoked by giving a device name (e.g. hk0, hp1, etc.). 114With no optional arguments 115it reads the first sector of the last track 116of the corresponding disk and prints out the bad sector information. 117It issues a warning if the bad sectors are out of order. 118.Nm Bad144 119may also be invoked with a serial number for the pack and a list 120of bad sectors. 121It will write the supplied information into all copies 122of the bad-sector file, replacing any previous information. 123Note, however, that 124.Nm bad144 125does not arrange for the specified sectors to be marked bad in this case. 126This procedure should only be used to restore known bad sector information which 127was destroyed. 128.Pp 129It is no longer necessary to reboot to allow the kernel 130to reread the bad-sector table from the drive. 131.Sh SEE ALSO 132.Xr badsect 8 , 133.Xr format 8 134.Sh BUGS 135It should be possible to format disks on-line under 136.Tn UNIX . 137.Pp 138It should be possible to mark bad sectors on drives of all type. 139.Pp 140On an 11/750, 141the standard bootstrap drivers used to boot the system do 142not understand bad sectors, 143handle 144.Tn ECC 145errors, or the special 146.Tn SSE 147(skip sector) errors of RM80-type disks. 148This means that none of these errors can occur when reading the file 149.Pa /vmunix 150to boot. Sectors 0-15 of the disk drive 151must also not have any of these errors. 152.Pp 153The drivers which write a system core image on disk after a crash do not 154handle errors; thus the crash dump area must be free of errors and bad 155sectors. 156.Sh HISTORY 157The 158.Nm 159command appeared in 160.Bx 4.1 . 161