diff options
Diffstat (limited to 'doc/sg_map.8')
-rw-r--r-- | doc/sg_map.8 | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/doc/sg_map.8 b/doc/sg_map.8 new file mode 100644 index 00000000..abe0935d --- /dev/null +++ b/doc/sg_map.8 @@ -0,0 +1,182 @@ +.TH SG_MAP "8" "May 2013" "sg3_utils\-1.36" SG3_UTILS +.SH NAME +sg_map \- displays mapping between Linux sg and other SCSI devices +.SH SYNOPSIS +.B sg_map +[\fI\-a\fR] [\fI-h\fR] [\fI\-i\fR] [\fI\-n\fR] [\fI\-scd\fR] [\fI\-sd\fR] +[\fI\-sr\fR] [\fI\-st\fR] [\fI\-V\fR] [\fI\-x\fR] +.SH DESCRIPTION +.\" Add any additional description here +.PP +Sometimes it is difficult to determine which SCSI device a sg device +name (e.g. /dev/sg0) refers to. This command loops through the +sg devices and finds the corresponding SCSI disk, cdrom or tape +device name (if any). Scanners are an example of SCSI devices +that have no alternate SCSI device name apart from their sg device +name. +.PP +This utility is deprecated and has not been updated for years, only very +obvious bugs will be fixed. Unless a very old version of Linux is being +used (e.g. 2.4 series or earlier), then please use a utility like lsscsi(8) +or the facilities offered by udev(8). +.SH OPTIONS +.TP +\fB\-a\fR +assume the sg devices have alphabetical device names and loop +through /dev/sga, /dev/sgb, etc. Default is numeric scan. +Note that sg device nodes with an alphabetical index have been +deprecated since the Linux kernel 2.2 series. +.TP +\fB\-h\fR +print usage message then exit. +.TP +\fB\-i\fR +in addition do a standard INQUIRY and output vendor, product and revision +strings for devices that are found. +.TP +\fB\-n\fR +assume the sg devices have numeric device names and loop +through /dev/sg0, /dev/sg1, etc. Default is numeric scan +.TP +\fB\-scd\fR +display mappings to SCSI cdrom device names of the form +/dev/scd0, /dev/scd1 etc +.TP +\fB\-sd\fR +display mappings to SCSI disk device names +.TP +\fB\-sr\fR +display mappings to SCSI cdrom device names of the form +/dev/sr0, /dev/sr1 etc +.TP +\fB\-st\fR +display mappings to SCSI tape device names +.TP +\fB\-V\fR +print out version string then exit (without further ado). +.TP +\fB\-x\fR +after each active sg device name is displayed there are +five digits: <host_number> <bus> <scsi_id> <lun> <scsi_type> +.SH NOTES +If no options starting with "\-s" are given then the mapping to +all SCSI disk, cdrom and tape device names is shown. +.PP +If the device file system (devfs) is present a line noting +this is output. The "native" devfs scsi hierarchy makes the +relationship between a sg device name and any corresponding +disk, cdrom or tape device name easy to establish. This +replaces the need for this command. However many applications +will continue to look for Linux SCSI device names in their +traditional places. [Devfs supplies a compatibility daemon +called devfsd whose default configuration adds back the +Linux device names in their traditional positions. +.PP +Quite often the mapping information can be derived by +observing the output of the command: "sg_map". +However if devices have been added since boot this can +be deceptive. +.PP +In the Linux kernel 2.6 series something close to the mapping +shown by this utility can be found by analysing sysfs. The +main difference is that sysfs analysis will show the mapping +between sg nodes and other SCSI device nodes in terms of +major and minor numbers. While major 8, minor 16 will usually +be /dev/sdb this is not necessarily so. Facilities associated +with udev may assign major 8, minor 16 some other device node +name. This version of sg_map has been extended to cope with +sparse disk device node names of the form "/dev/sd<str>" +where <str> can be one of [a\-z,aa\-zz,aaa\-zzz]. See the sg_map26 +utility for a more precise way (i.e. less directory scanning) +for mapping between sg device names and higher level names; +including finding user defined names. +.PP +This utility was written at a time when hotplugging of SCSI devices +was not supported in Linux. It used a simple algorithm to scan sg +device nodes in ascending numeric or alphabetical order, stopping +after there were 5 consecutive errors. +.PP +In the Linux kernel 2.6 series, this utility uses sysfs to find which +sg device nodes are active and only checks those. Hence there can be +large "holes" in the numbering of sg device nodes (e.g. after an +adapter has been removed) and still all active sg device nodes will +be listed. This utility assumes that sg device nodes are named using +the normal conventions and searches from /dev/sg0 to /dev/sg4095 +inclusive. +.SH EXAMPLES +.PP +My system has a SCSI disk, a cd writer and a dvd player: +.br + $ sg_map +.br + # Note: the devfs pseudo file system is present +.br + /dev/sg0 /dev/sda +.br + /dev/sg1 /dev/sr0 +.br + /dev/sg2 /dev/sr1 +.PP +In order to find which sg device name corresponds to the disk: +.br + $ sg_map \-sd +.br + # Note: the devfs pseudo file system is present +.br + /dev/sg0 /dev/sda +.br + /dev/sg1 +.br + /dev/sg2 +.PP +The "\-x" option gives the following output: +.br + sg_map \-x +.br + # Note: the devfs pseudo file system is present +.br + /dev/sg0 1 0 1 0 0 /dev/sda +.br + /dev/sg1 2 0 4 0 5 /dev/sr0 +.br + /dev/sg2 2 0 6 0 5 /dev/sr1 +.PP +When a SCSI scanner is added the output becomes: +.br + $ sg_map +.br + # Note: the devfs pseudo file system is present +.br + /dev/sg0 /dev/sda +.br + /dev/sg1 /dev/sr0 +.br + /dev/sg2 /dev/sr1 +.br + /dev/sg3 +.PP +By process of elimination /dev/sg3 must be the scanner. +.SH EXIT STATUS +The exit status of sg_map is 0 when it is successful. Otherwise see +the sg3_utils(8) man page. +.SH AUTHOR +Written by Douglas Gilbert +.SH "REPORTING BUGS" +Report bugs to <dgilbert at interlog dot com>. +.SH COPYRIGHT +Copyright \(co 2000\-2013 Douglas Gilbert +.br +This software is distributed under the GPL version 2. There is NO +warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. +.SH "SEE ALSO" +.B sg_map26(8) +, +.B scsi_info(8) +, +.B scsidev(8) +, +.B devfsd(8) +, +.B lsscsi(8) +, +.B udev(7) |