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