Ubuntu Manpage: lsscsi - list SCSI devices (or hosts) and their attributes

NAME

       lsscsi - list SCSI devices (or hosts) and their attributes

SYNOPSIS

       lsscsi  [--classic]  [--device]  [--generic]  [--help]  [--hosts]  [--kname] [--list] [--lunhex] [--long]
       [--protection] [--protmode] [--scsi_id] [--size] [--sysfsroot=PATH] [--transport] [--verbose] [--version]
       [--wwn] [H:C:T:L]

DESCRIPTION

Uses information in sysfs (Linux kernel series 2.6 and later) to list SCSI devices (or hosts) currently
attached to the system. Options can be used to control the amount and form of information provided for
each device.

If a H:C:T:L argument is given then it acts as a filter and only devices that match it are listed. The
colons don't have to be present, and '-', '*', '?' or missing arguments at the end are interpreted as
wildcards. The default is '*:*:*:*' which means to match everything. Any filter string using '*' of '?'
should be surrounded by single or double quotes to stop shell expansions. If '-' is used as a wildcard
then the whole filter argument should be prefixed by '-- ' to tell this utility there are no more options
on the command line to be interpreted. A leading '[' and trailing ']' are permitted (e.g. '[1:0:0]'
matches all LUNs on 1:0:0). May also be used to filter --hosts in which case only the H is active and may
be either a number or in the form "host<n>" where <n> is a host number.

By default in this utility device node names (e.g. "/dev/sda" or "/dev/root_disk") are obtained by noting
the major and minor numbers for the listed device obtained from sysfs (e.g. the contents of
"/sys/block/sda/dev") and then looking for a match in the "/dev" directory. This "match by major and
minor" will allow devices that have been given a different name by udev (for example) to be correctly
reported by this utility.

In some situations it may be useful to see the device node name that Linux would produce by default, so
the --kname option is provided. An example of where this may be useful is kernel error logs which tend
to report disk error messages using the disk's default kernel name.

OPTIONS

Arguments to long options are mandatory for short options as well. The options are arranged in
alphabetical order based on the long option name.

-c, --classic
The output is similar to that obtained from 'cat /proc/scsi/scsi'

-d, --device
After outputting the (probable) SCSI device name the device node major and minor numbers are shown
in brackets (e.g. "/dev/sda[8:0]").

-g, --generic
Output the SCSI generic device file name. Note that if the sg driver is a module it may need to be
loaded otherwise '-' may appear.

-h, --help
Output the usage message and exit.

-H, --hosts
List the SCSI hosts currently attached to the system. If this option is not given then SCSI
devices are listed.

-k, --kname
Use Linux default algorithm for naming devices (e.g. block major 8, minor 0 is "/dev/sda") rather
than the "match by major and minor" in the "/dev" directory as discussed above.

-L, --list
Output additional information in <attribute_name>=<value> pairs, one pair per line preceded by two
spaces. This option has the same effect as '-lll'.

-l, --long
Output additional information for each SCSI device (host). Can be used multiple times for more
output in which case the shorter option form is more convenient (e.g. '-lll'). When used three
times (i.e. '-lll') outputs SCSI device (host) attributes one per line; preceded by two spaces; in
the form "<attribute_name>=<value>".

-x, --lunhex
when this option is used once the LUN in the tuple (at the start of each device line) is shown in
"T10" format which is up to 16 hexadecimal digits. It is prefixed by "0x" to distinguish the LUN
from the decimal value shown in the absence of this option. Also hierarchal LUNs are shown with a
"_" character separating the levels. For example the two level LUN: 0x0355006600000000 will appear
as 0x0355_0066. If this option is given twice (e.g. using the short form: '-xx') then the full 16
hexadecimal digits are shown for each LUN, prefixed by "0x".

-p, --protection
Output target (DIF) and initiator (DIX) protection types.

-P, --protmode
Output effective protection information mode for each disk device.

-i, --scsi_id
outputs the udev derived matching id found in /dev/disk/by-id/scsi* . This is only for disk (and
disk like) devices. If no match is found then "dm-uuid-mpath*" and "usb*" are searched in the same
directory. If there is still no match then the /sys/class/block/<disk>/holders directory is
searched. The matching id is printed following the device name (e.g. /dev/sdc) and if there is no
match "-" is output.

-s, --size
Print disk capacity in human readable form.

-t, --transport
Output transport information. This will be a target related information or, if --hosts is given,
initiator related information. When used without --list, a name or identifier (or both) are output
on a single line, usually prefixed by the type of transport. For devices this information replaces
the normal vendor, product and revision strings. When the --list option is also given then
additionally multiple lines of attribute_name=value pairs are output, each indented by two spaces.
See the section on transports below.

-v, --verbose
outputs directory names where information is found. Use multiple times for more output.

-V, --version
outputs version information then exits.

-w, --wwn
outputs the WWN for disks instead of manufacturer, model and revision (or instead of transport
information). The World Wide Name (WWN) is typically 64 bits long (16 hex digits) but could be up
to 128 bits long. To indicate the WWN is hexadecimal, it is prefixed by "0x".

-y, --sysfsroot=PATH
assumes sysfs is mounted at PATH instead of the default '/sys' . If this option is given PATH
should be an absolute path (i.e. start with '/').

TRANSPORTS

This utility lists SCSI devices which are known as logical units (LU) in the SCSI Architecture Model
(ref: SAM-4 at http://www.t10.org) or hosts when the --hosts option is given. A host is called an
initiator in SAM-4. A SCSI command travels out via an initiator, across some transport to a target and
then onwards to a logical unit. A target device may contain several logical units. A target device has
one or more ports that can be viewed as transport end points. Each FC and SAS disk is a single target
that has two ports and contains one logical unit. If both target ports on a FC or SAS disk are connected
and visible to a machine, then lsscsi will show two entries. Initiators (i.e. hosts) also have one or
more ports and some HBAs in Linux have a host entry per initiator port while others have a host entry per
initiator device.

When the --transport option is given for devices (i.e. --hosts not given) then most of the information
produced by lsscsi is associated with the target, or more precisely: the target port, through which SCSI
commands pass that access a logical unit.

Typically this utility provides one line of output per "device" or host. Significantly more information
can be obtained by adding the --list option. When used together with the --transport option, after the
summary line, multiple lines of transport specific information in the form "<attribute_name>=<value>" are
output, each indented by two spaces. Using a filter argument will reduce the volume of output if a lot
of devices or hosts are present.

The transports that are currently recognized are: IEEE 1394, ATA, FC, iSCSI, SAS, SATA, SPI and USB.

For IEEE 1394 (a.k.a. Firewire and "SBP" when storage is involved), the EUI-64 based target port name is
output when --transport is given, in the absence of the --hosts option. When the --hosts option is given
then the EUI-64 initiator port name is output. Output on the summary line specific to the IEEE 1394
transport is prefixed by "sbp:".

to detect ATA and SATA a crude check is performed on the driver name (after the checks for other
transports are exhausted). Based on the driver name either ATA or SATA transport type is chosen. Output
on the summary line is either "ata:" or "sata:". No other attributes are given. Most device and hosts
flagged as "ata:" will use the parallel ATA transport (PATA).

For Fibre Channel (FC) the port name and port identifier are output when --transport is given. In the
absence of the --hosts option these ids will be for the target port associated with the device (logical
unit) being listed. When the --hosts option is given then the ids are for the initiator port used by the
host. Output on the summary line specific to the FC transport is prefixed by "fc:". If FCoE (over
Ethernet) is detected the prefix is changed to "fcoe:".

For iSCSI the target port name is output when --transport is given, in the absence of the --hosts option.
This is made up of the iSCSI name and the target portal group tag. Since the iSCSI name starts with "iqn"
no further prefix is used. When the --hosts option is given then only "iscsi:" is output on the summary
line.

For Serial Attached SCSI the SAS address of the target port (or initiator port if --hosts option is also
given) is output. This will be a naa-5 address. For SAS HBAs and SAS targets (such as SAS disks and tape
drives) the SAS address will be world wide unique. For SATA disks attached to a SAS expander, the
expander provides the SAS address by adding a non zero value to its (i.e. the expander's) SAS address
(e.g. expander_sas_address + phy_id + 1). SATA disks directly attached to SAS HBAs seem to have an
indeterminate SAS address. Output on the summary line specific to the SAS transport is prefixed by
"sas:".

For the SCSI Parallel Interface (SPI) the target port identifier (usually a number between 0 and 15
inclusive) is output when --transport is given, in the absence of the --hosts option. When the --hosts
option is given then only "spi:" is output on the summary line.

When a USB transport is detected, the summary line will contain "usb:" followed by a USB device name. The
USB device name has the form "<b>-<p1>[.<p2>[.<p3>]]:<c>.<i>" where <b> is the USB bus number, <p1> is
the port on the host. <p2> is a port on a host connected hub, if present. If needed <p3> is a USB hub
port closer to the USB storage device. <c> refers to the configuration number while <i> is the interface
number. There is a separate SCSI host for each USB (SCSI) target. A USB SCSI target may contain multiple
logical units. Thus the same "usb: <device_name>" string appears for a USB SCSI host and all logical
units that belong to the USB SCSI target associated with that USB SCSI host.

LUNS

For historical reasons and as used by several other Unix based Operating Systems, Linux uses a tuple of
integers to describe (a path to) a SCSI device (also know as a Logical Unit (LU)). The last element of
that tuple is the so-called Logical Unit Number (LUN). And originally in SCSI a LUN was an integer, at
first 3 bits long, then 8 then 16 bits. SCSI LUNs today (SAM-5 section 4.7) are 64 bits but SCSI
standards now consider a LUN to be an array of 8 bytes.

Up until 2013, Linux mapped SCSI LUNs to a 32 bit integer by taking the first 4 bytes of the SCSI LUN and
ignoring the last 4 bytes. Linux treated the first two bytes of the SCSI LUN as a unit (a word) and it
became the least significant 16 bits in the Linux LUN integer. The next two bytes of the SCSI LUN became
the upper 16 bits in the Linux LUN integer. The rationale for this was to keep commonly used LUNs small
Linux LUN integers. The most common LUN (by far) in SCSI LUN (hex) notation is 00 00 00 00 00 00 00 00
and this becomes the Linux LUN integer 0. The next most common LUN is 00 01 00 00 00 00 00 00 and this
becomes the Linux LUN integer 1.

In 2013 it is proposed to increase Linux LUNs to a 64 bit integer by extending the mapping outlined
above. In this case all information that is possible to represent in a SCSI LUN is mapped a Linux LUN (64
bit) integer. And the mapping can be reversed without losing information.

This version of the utility supports both 32 and 64 bit Linux LUN integers. By default the LUN shown at
the end of the tuple commencing each line is a Linux LUN as a decimal integer. When the --lunhex option
is given then the LUN is in SCSI LUN format with the 8 bytes run together, with the output in hexadecimal
and prefixed by '0x'. The LUN is decoded according to SAM-5's description and trailing zeros (i.e. digits
to the right) are not shown. So LUN 0 (i.e. 00 00 00 00 00 00 00 00) is shown as 0x0000 and LUN 65 (i.e.
00 41 00 00 00 00 00 00) is shown as 0x0041. If the --lunhex option is given twice then the full 64 bits
(i.e. 16 hexadecimal digits) are shown.

If the --lunhex option is not given on the command line then the environment variable LSSCSI_LUNHEX_OPT
is checked. If LSSCSI_LUNHEX_OPT is present then its associated value becomes the number of times the
--lunhex is set internally. So, for example, 'LSSCSI_LUNHEX_OPT=2 lsscsi' and 'lsscsi -xx' are
equivalent.

EXAMPLES

       Information    about    this    utility    including    examples    can     also     be     found     at:
       http://sg.danny.cz/scsi/lsscsi.html .

NOTES

       Information  for  this  command  is derived from the sysfs file system, which is assumed to be mounted at
       /sys unless specified otherwise by the user.  SCSI (pseudo) devices that have been detected by  the  SCSI
       mid  level will be listed even if the required upper level drivers (i.e. sd, sr, st, osst or ch) have not
       been loaded. If the appropriate upper level driver has not been loaded then the  device  file  name  will
       appear  as  '-'  rather  than something like '/dev/st0'. Note that some devices (e.g. scanners and medium
       changers) do not have a primary upper level driver and can only be  accessed  via  a  SCSI  generic  (sg)
       device name.

       Generic  SCSI  devices  can  also  be accessed via the bsg driver in Linux.  By default, the bsg driver's
       device node names are of the form '/dev/bsg/H:C:T:L'. So, for example, the  SCSI  device  shown  by  this
       utility  on  a  line  starting  with  the  tuple  '6:0:1:2' could be accessed via the bsg driver with the
       '/dev/bsg/6:0:1:2' device node name.

       lsscsi version 0.21 or later is required to correctly display SCSI devices in Linux  kernel  2.6.26  (and
       possibly later) when the CONFIG_SYSFS_DEPRECATED_V2 kernel option is not defined.

AUTHOR

       Written by Doug Gilbert

REPORTING BUGS

       Report bugs to <dgilbert at interlog dot com>.

COPYRIGHT

       Copyright © 2003-2013 Douglas Gilbert
       This  software is distributed under the GPL version 2. There is NO warranty; not even for MERCHANTABILITY
       or FITNESS FOR A PARTICULAR PURPOSE.