Ubuntu Manpage: smp_* - invoke a SAS Serial Management Protocol (SMP) function

NAME

       smp_* - invoke a SAS Serial Management Protocol (SMP) function

SYNOPSIS

       smp_*   [--expected=EX]   [--help]   [--hex]  [--interface=PARAMS]  [--raw]  [--sa=SAS_ADDR]  [--verbose]
       [--version] SMP_DEVICE[,N]

DESCRIPTION

       Serial Attached SCSI (SAS) is a transport (also known as a interconnect) used by storage systems.  A  SAS
       system is made up of Host Bus Adapters (HBAs typically containing SCSI initiators), disks (referred to in
       SCSI  as  both  targets  and  logical  units)  and optionally some switching hardware called "expanders".
       Expanders are not SCSI devices so a new protocol was required to control and monitor them. Its full  name
       is the SAS Serial Management Protocol which is abbreviated to SMP.

       smp_utils  is  a package of utilities. Each utility sends an SMP function request to a SMP_DEVICE (an SMP
       target). Some utilities may invoke the same function more than once. If an error  occurs  then  an  error
       message is sent to stderr. If no error occurs, the response is decoded (the default), output in ASCII hex
       (when --hex is given) or output in binary to stdout (when the --raw option is given).

       If SMP_DEVICE[,N] is not given then the value in the environment variable SMP_UTILS_DEVICE is used.

       This package was originally written for Linux and has been ported to FreeBSD and Solaris.

LINUX INTERFACE

Currently there are multiple interfaces that allow SMP functions to be passed through to an SMP target.

One method is to have a SMP_DEVICE which is actually the SMP initiator (e.g. '/dev/mptctl,0'). In this
case the SMP target's SAS address must be supplied with the --sa=SAS_ADDR option.

Another method is to have a SMP_DEVICE which represents the SMP target. In this case no SAS_ADDRESS
needs to be given (since it is implicit).

Each utility in smp_utils attempts to work out which interface it has been given by examining the
SMP_DEVICE file. There are two interfaces supported currently:

mpt This specifies the MPT fusion SAS pass-through. The mptsas driver uses the '/dev/mptctl' device
node (character device major 10, minor 220) while the mpt2sas driver uses '/dev/mpt2ctl' device
node (major 10, minor 221). The 'modprobe mptctl' or 'modprobe mpt2ctl' command may be needed. If
there are multiple mpt fusion controllers (HBAs) in the computer, then the user will need to
specify which one to use with the syntax: '/dev/mptctl,<n>' where <n> is the "ioc_num". This
number can be found with dmesg after the mptsas driver is registered and appears as a suffix to
the driver name (e.g. mpt2sas0). It can also be found in
'/sys/class/scsi_host/host<n>/unique_id'. When this interface is used the --sa=SAS_ADDR option
must be given to specify the SAS address of the SMP target.

sgv4 (sg)
This interface is more generic and supported by several SAS HBA drivers including mptsas (and
mpt2sas). It was introduced in the linux 2.6.24 kernel. The SMP functions are passed to the kernel
using a format known as "SCSI Generic Version 4" which gives this interface its name: "sgv4" or
just "sg". The SAS transport layer within the SCSI sub-system unpacks the SMP requests and
forwards them to SAS low level drivers that support this interface. The SMP_DEVICE is either a
member of the '/sys/class/bsg' directory (e.g. /sys/class/bsg/expander-6:0 ) or a device node made
for the bsg driver (e.g. /dev/bsg/expander-6:0 ). Such device nodes are dynamic (i.e. they don't
have fixed major and minor numbers) and should correspond to the major and minor numbers found in
the 'sys/class/bsg/<smp_target_device>/dev' file.

FREEBSD INTERFACE

       The  CAM  subsystem  has  been  enhanced  in  FreeBSD  9  to  pass-through  SMP  requests  and return the
       corresponding responses. However CAM does not directly access expander devices because they are not  SCSI
       devices. It makes the assumption that each SAS expander has an integrated SES (enclosure) device and that
       is  addressed.  This  assumption  seems to be true for SAS-2 expanders but not some SAS-1 expanders. Thus
       invocations look like this:

         # smp_discover /dev/ses0

       where /dev/ses0 is a SES device associated with a SAS expander.

SOLARIS INTERFACE

       The USMP pass-through mechanism is used. Invocations look like this:

         # smp_rep_manufacturer /dev/smp/expd0

ENVIRONMENT VARIABLES

       If the device name is not given then the SMP_UTILS_DEVICE environment variable is checked and if  present
       its contents are used as the device name.

       If  the  SAS address (of the SMP target) is not given and it is required (i.e.  it is not implicit in the
       device name) then the SMP_UTILS_SAS_ADDR environment variable is checked and if present its contents  are
       used  as  the SAS address. SAS addresses are usually given in hex indicated by a leading '0x' or trailing
       'h'.

       In both cases command line options override the corresponding environment variable.

COMMON OPTIONS

Mandatory arguments to long options are mandatory for short options as well. If an option takes a
numeric argument then that argument is assumed to be decimal unless otherwise indicated (e.g. with a
leading "0x" or a trailing "h").

-E, --expected=EX
revision 4a of the SAS-2 draft introduced an 'expected expander change count' field in some SMP
requests. The idea is to detect other SMP initiators trying to change the state of an expander.
The value EX is from 0 to 65535 inclusive with 0 being the default value. When EX is greater than
zero then if the value doesn't match the expander change count of the SMP target (i.e. the
expander) when the request arrives then the target ignores the request and sets a function result
of "invalid expander change count" in the response.

-h, --help
output the usage message for the utility then exit.

-H, --hex
output the response in hexadecimal. This does not include the trailing CRC field.

-I, --interface=PARAMS
interface specific parameters. This option is usually not needed since the interface type is
guessed by a utility based on the characteristics of the given SMP_DEVICE argument or what is in
the corresponding environment variables. PARAMS is of the form: INTF[,force]. If the guess
doesn't work then the interface can be specified by giving a INTF of either 'mpt' or 'sgv4'.
Sanity checks are still performed and a utility may refuse if it doesn't agree with the given
INTF. If the user is really sure then adding a ',force' will force the utility to use the given
interface.

-r, --raw
send the response to stdout in binary. This does not include the trailing CRC field. All error
messages are sent to stderr.

-s, --sa=SAS_ADDR
specifies the SAS address of the SMP target device. Typically this is an expander. This option may
not be needed if the SMP_DEVICE has the target's SAS address associated with it. The SAS_ADDR is
in decimal but most SAS addresses are shown in hexadecimal. To give a number in hexadecimal either
prefix it with '0x' or put a trailing 'h' on it. If this option is not given then the value in the
environment variable SMP_UTILS_SAS_ADDR is used.

-v, --verbose
increase the verbosity of the output. Can be used multiple times.

-V, --version
print the version string and then exit.

EXIT STATUS

       To aid scripts that call these utilities, the exit status is set to indicate success (0) or failure (1 or
       more):

       0      success

       1 - 63 reserved  for  SMP  function  result  codes. See the SAS-2 (or later) draft, in the section on the
              application layer, drilling down further: management application layer then  SMP  functions.  Here
              are  some common function result codes: 1 [unknown SMP function], 2 [SMP function failed], 16 [phy
              does not exist], 17 [index does not exist], 18 [phy  does  not  support  SATA],  19  [unknown  phy
              operation], 22 [phy vacant] and 35 [zone lock violation].

       91     syntax  error. Either illegal options, options with bad arguments or a combination of options that
              is not permitted.

       92     the utility is unable to open, close or use the given SMP_DEVICE.  The given file  name  could  be
              incorrect  or  there  may  be  file permission problems. Adding the --verbose option may give more
              information.

       97     the response to an SMP function failed sanity checks.

       99     any error that can't be categorized into values 1 to 97  may  yield  this  value.   This  includes
              transport and operating system errors.

NOTES

Finding the SAS address of an expander can be a challenge in some environments. An enclosure containing
one or more expanders may have the expander SAS address(es) printed on the back of the device, a bit like
Ethernet MAC addresses.

In the Linux 2.6 kernel series the expander SAS address may well be in the sysfs tree but it is not
always easy to find. Doing this search may help:

# find /sys -name "*expander*"

That should show the suffix on any expanders that have been detected. Then a command like 'cat
/sys/class/sas_device/expander-6:0/sas_address' should show its SAS address.

Another approach is to work backwards from SCSI devices (i.e. logical units). The protocol specific port
log page (log page 18h) contains fields for the "attached SAS address". The sg_logs utility from the
sg3_utils package could be used like this:

# sg_logs --page=18h /dev/sdb

Any given "attached SAS address" is either a HBA, an expander or 0 indicating that port is not connected.
An expander is indicated by "attached device type: expander device". A SAS disk's target port identifiers
(also known as SAS addresses), device name and logical unit name (all NAA 5 format) can be found with the
sg_vpd utility (e.g. 'sg_vpd -i <disk_dev>'). The sdparm utility can provide the same information (e.g.
'sdparm -i <disk_dev>').

A SAS expander is often associated with a SCSI Enclosure Services (SES) device sometimes on the same
silicon attached via a virtual phy to the expander. That SES device may be able to access and control an
attached enclosure or backplane via SGPIO or I2C on sideband signals (e.g. in a SFF-8087 cable). To
interact with a SES device, see the sg_ses utility.

Often expander phys are grouped in fours on the same connector (e.g. SFF-8088). Care needs to be taken
when multiple expanders are interconnected. An enclosure universal port is one in which the "table to
table supported" attribute is set (in the REPORT GENERAL response) and the associated phys have the table
routing attribute (in the DISCOVER response). Enclosure universal ports were introduced in SAS-2 and have
no restrictions when used to interconnect expanders or connect end devices. An enclosure out port is one
in which the "table to table supported" attribute is clear and the associated phys have the table routing
attribute. An enclosure in port is one in which the associated phys have the subtractive routing
attribute. When universal ports are not available, an expander interconnect should be between an in port
and an out port.

EXAMPLES

       See "Examples" section in http://sg.danny.cz/sg/smp_utils.html .

CONFORMING TO

SAS has multiple generations. The first three generations are approved standards: the original SAS (ANSI
INCITS 376-2003), SAS 1.1 (INCITS 417-2006) and SAS-2 (ANSI INCITS 457-2010) . SAS-2.1 technical work is
ongoing and it has been split into two documents, the one of interest is called the SAS Protocol Layer
(SPL) and at the time of writing the most recent draft is spl-r07.pdf (see section 9.4.3 for SMP
functions). Technical work on SAS-3 has started with the SMP functions defined in the SPL-2 document
(spl2r03.pdf). To avoid confusion, the multiple generations of SAS will be referred to in these man pages
as SAS 1, 1.1, 2, 2.1 and 3 . Drafts, including those just prior to standardization can be found at the
http://www.t10.org site. INCITS policy now requires a registration to view these drafts, a break from
t10.org tradition.

The two utilities for reading and writing to GPIO registers, smp_read_gpio and smp_write_gpio, are
defined in the Small Form Factor document SFF-8485 found at http://www.sffcommittee.com . "Enhanced"
versions of the corresponding SMP functions have been mentioned in some drafts but no definitions have
been published and the references have been removed in more recent drafts.

In this section of each utility's man page is the first standard in which the associated SMP function
appeared and whether there have been significant additions in later standards.

The COVERAGE file in the smp_utils source tarball shows a table of all SMP function names defined in the
drafts, the versions of those standards in which those SMP functions first appeared and the corresponding
smp_utils utility names. A lot of extra SMP functions have been added in SAS-2 associated with zoning.

AUTHORS

       Written by Douglas Gilbert.

REPORTING BUGS

       Report bugs to <dgilbert at interlog dot com>.

COPYRIGHT

       Copyright © 2006-2012 Douglas Gilbert
       This  software is distributed under a FreeBSD license. There is NO warranty; not even for MERCHANTABILITY
       or FITNESS FOR A PARTICULAR PURPOSE.