SG_MAP(8)							     SG3_UTILS								 SG_MAP(8)

NAME

       sg_map - displays mapping between linux sg and other SCSI devices

SYNOPSIS

       sg_map [-a] [-h] [-i] [-n] [-scd] [-sd] [-sr] [-st] [-V] [-x]

DESCRIPTION

       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.

OPTIONS

       -a     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.

       -h     print usage message then exit.

       -i     in addition do a standard INQUIRY and output vendor, product and revision strings for devices that are found.

       -n     assume the sg devices have numeric device names and loop through /dev/sg0, /dev/sg1, etc. Default is numeric scan

       -scd   display mappings to SCSI cdrom device names of the form /dev/scd0, /dev/scd1 etc

       -sd    display mappings to SCSI disk device names

       -sr    display mappings to SCSI cdrom device names of the form /dev/sr0, /dev/sr1 etc

       -st    display mappings to SCSI tape device names

       -V     print out version string then exit (without further ado).

       -x     after each active sg device name is displayed there are five digits: <host_number> <bus> <scsi_id> <lun> <scsi_type>

NOTES

       If no options starting with "-s" are given then the mapping to all SCSI disk, cdrom and tape device names is shown.

       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.

       Quite  often the mapping information can be derived by observing the output of the command: "cat /proc/scsi/scsi".  However if devices have
       been added since boot this can be deceptive.

       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.

       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.

       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  inclu-
       sive.

EXAMPLES

       My system has a SCSI disk, a cd writer and a dvd player:
	  $ sg_map
	  # Note: the devfs pseudo file system is present
	  /dev/sg0  /dev/sda
	  /dev/sg1  /dev/sr0
	  /dev/sg2  /dev/sr1

       In order to find which sg device name corresponds to the disk:
	  $ sg_map -sd
	  # Note: the devfs pseudo file system is present
	  /dev/sg0  /dev/sda
	  /dev/sg1
	  /dev/sg2

       The "-x" option gives the following output:
	  sg_map -x
	  # Note: the devfs pseudo file system is present
	  /dev/sg0  1 0 1 0  0	/dev/sda
	  /dev/sg1  2 0 4 0  5	/dev/sr0
	  /dev/sg2  2 0 6 0  5	/dev/sr1

       When a SCSI scanner is added the output becomes:
	  $ sg_map
	  # Note: the devfs pseudo file system is present
	  /dev/sg0  /dev/sda
	  /dev/sg1  /dev/sr0
	  /dev/sg2  /dev/sr1
	  /dev/sg3

       By process of elimination /dev/sg3 must be the scanner.

EXIT STATUS

       The exit status of sg_map is 0 when it is successful. Otherwise see the sg3_utils(8) man page.

AUTHOR

       Written by Doug Gilbert

REPORTING BUGS

       Report bugs to <dgilbert at interlog dot com>.

COPYRIGHT

       Copyright (C) 2000-2006 Douglas Gilbert
       This  software  is distributed under the GPL version 2. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
       POSE.

SEE ALSO

       sg_map26(8) , scsi_info(8) , scsidev(8) , devfsd(8)

sg3_utils-1.23							   December 2006							 SG_MAP(8)