.TH SG_SCAN "8" "December 2012" "sg3_utils\-1.35" SG3_UTILS
.SH NAME
sg_scan \- scan storage devices and map to volume names
.SH SYNOPSIS
.B sg_scan
[\fI\-\-bus\fR]  [\fI\-\-help\fR] [\fI\-\-letter=VL\fR] [\fI\-\-scsi\fR]
[\fI\-\-verbose\fR] [\fI\-\-version\fR]
.SH DESCRIPTION
.\" Add any additional description here
.PP
This utility scans for physical drives (a.k.a. "hard drives"), cd/dvd drives
and tape drives and maps them to the corresponding volumes. There may be
many, one or no corresponding volumes. There is one line output per device
with identification strings to the right. Its purpose is to list the
storage device names that can be used by other utilities in this package.
.PP
There is an optional SCSI adapter scan which may find additional storage
devices other than the ones listed above. An example is a SCSI Enclosure
Services (SES) device typically found in disk arrays. 
.PP
Storage and related devices can have several device names in Windows.
Probably the most common in the volume name (e.g. "D:"). There is also
a "class" device name, and this utility scans for three of
them: "PhysicalDrive<n>", "CDROM<n>" and "TAPE<n>". <n> is an integer
starting at 0 allocated in ascending order as devices are discovered (and
sometimes rediscovered).
.PP
Some storage devices have a SCSI lower level device name which starts
with a SCSI (pseudo) adapter name of the form "SCSI<n>:". To this is added
sub\-addressing in the form of a "bus" number, a "target" identifier and
a LUN (Logical Unit Number). The "bus" number is also known as a "PathId".
These components are combined by the utility to make a device name of the
form: "SCSI<n>:<bus>,<target>,<lun>". This utility allows the
trailing ",<lun>" to be omitted in which case a LUN of zero is assumed. This
lower level device name cannot often be used directly since Windows blocks
attempts to use it if a class driver has "claimed" the device. There are
SCSI device types (e.g. Automation/Drive interface type) for which there is
no class driver. At least two transports ("bus types" in Windows jargin):
USB and IEEE 1394 do not have a "scsi" device names of this form.
.PP
In keeping with DOS file system conventions, the various device names
can be given in upper, lower or mixed case. Since "PhysicalDrive<n>" is
tedious to write, a shortened form of "PD<n>" is permitted by all
utilities in this package.
.PP
A single device (e.g. a disk) can have many device names! For
example: "PDO" can also be "C:", "D:" and "SCSI0:0,1,0". The two volume names
reflect that the disk has two partitions on it. Disk partitions that are
not recognised by Windows are not usually given a volume name. However
Vista does show a volume name for a disk which has no partitions recognised
by it and when selected invites the user to format it (which is rather
unfriendly to other OSes).
.PP
The scanning logic and output of this command changed significantly in
sg3_utils version 1.27 . The SCSI adapter based scanned is now an
optional extra.
.PP
For more information see the NOTES section below.
.SH OPTIONS
Arguments to long options are mandatory for short options as well.
.TP
\fB\-b\fR, \fB\-\-bus\fR
show the bus type (or transport) by which the device is attached to the
operating systems. Two or more transports may be involved. For example,
a SATA disk may be in the external enclosure connected to the computer via
USB in which case the bus type is USB.
.TP
\fB\-h\fR, \fB\-\-help\fR
outputs the usage message summarizing command line options
then exits.
.TP
\fB\-l\fR, \fB\-\-letter\fR=\fIVL\fR
normally a device that has multiple volume names has up to four listed. If
there are more than that a "+" is added after the fourth. When this option
is given the \fIVL\fR argument is assumed to be a volume name (i.e. 'C'
to 'Z') and if found in the scan, only that volume name appears in the
output. If there are novolume names in the output then \fIVL\fR was not
found.
.TP
\fB\-s\fR, \fB\-\-scsi\fR
do a SCSI adapter based scan after the normal storage device based scan.
There is a blank line between the normal scan and the SCSI adapter based
scan. If this option is given twice then only the SCSI adapter based scan
is done.
.TP
\fB\-v\fR, \fB\-\-verbose\fR
increases the level or verbosity. Can be used multiple times to display
more of the internal data, both in normal and error processing.
.TP
\fB\-V\fR, \fB\-\-version\fR
print out version string
.SH NOTES
This utility does not support Windows 95, 98 and ME (and earlier Windows
operating systems). The target Windows operating systems are currently
Windows 2000, 2003, XP and Vista (and their variants).
.PP
When the \fI\-\-scsi\fR option is given the SCSI adapter tuple is followed
by a list of two or three fields. First is "claimed=0|1" indicating whether
a class driver has claimed the device. The next field is "pdt=<num>"
where <num> is the "peripheral device type" as defined in the SCSI INQUIRY
command (see SPC\-4 at http://www.t10.org). The <num> has a trailing "h" to
indicate that it is hexadecimal. Sometimes a third field with the
word "dubious" appears. This flags that what is supposed to be a SCSI
INQUIRY command response has a badly formed "additional length" field.
Thus the corresponding device is unlikely to be a native SCSI device.
.PP
The DOS device names given the the CreateFile() call all start with
a "\\\\.\\" string. That can be given but if not will be supplied
automatically.
.PP
Scanning devices that are hot unplugged and replugged often can be
problematic, especially with the class device names. Each time a device is
removed and re\-added it gets a larger class device name (e.g. "PD3"
becomes "PD4" leaving "PD3" unused). This utility stops scanning class
devices after it find 8 consecutive "holes".
.SH EXAMPLES
The following examples are from a laptop with an internal drive (SATA), a
CD/DVD drive and a USB attached SATA disk. The latter disk has two volumes
recognised by Windows.
.PP
  # sg_scan
.br
PD0     [C]     FUJITSU   MHY2160BH         0000  
.br
PD1     [DF]    WD        2500BEV External  1.05  WD\-WXE90     
.br
CDROM0  [E]     MATSHITA DVD/CDRW UJDA775  CB03
.PP
Now request bus types as well. BTW That is a SATA disk holding volume C:
and there is a "Sata" bus type.
.PP
  # sg_scan \-b
.br
PD0     [C]     <Ata  >  FUJITSU   MHY2160BH         0000  
.br
PD1     [DF]    <Usb  >  WD        2500BEV External  1.05  WD\-WXE90
.br
CDROM0  [E]     <Atapi>  MATSHITA DVD/CDRW UJDA775  CB03
.PP
Now request a SCSI adapter scan as well.
.PP
  # sg_scan \-b \-s
.br
PD0     [C]     <Ata  >  FUJITSU   MHY2160BH         0000  
.br
PD1     [DF]    <Usb  >  WD        2500BEV External  1.05  WD\-WXE90     
.br
CDROM0  [E]     <Atapi>  MATSHITA DVD/CDRW UJDA775  CB03  
.br
   
.br
SCSI0:0,0,0   claimed=1 pdt=0h  FUJITSU   MHY2160BH         0000
.br
SCSI1:0,0,0   claimed=1 pdt=5h  MATSHITA  DVD/CDRW UJDA775  CB03
.PP
.SH EXIT STATUS
The exit status of sg_scan is 0 when it is successful. Otherwise see
the sg3_utils(8) man page.
.SH AUTHORS
Written by D. Gilbert
.SH COPYRIGHT
Copyright \(co 2006\-2012 Douglas Gilbert
.br
This software is distributed under a FreeBSD license. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
