SMP_UTILS(8) SMP_UTILS SMP_UTILS(8)
NAME
smp_* - invoke a Serial Attached SCSI Management (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 Management Protocol which is abbreviated to SMP.
smp_utils is a package of utilities. Each utility sends a SMP function request to a SMP_DEVICE (a 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.
INTERFACE
Currently there are multiple interfaces that allow SMP functions to be passed through to a 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.
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 char-
acteristics 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 fur-
ther: 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 per-
mission problems. Adding the --verbose option may give more information.
97 the response to a 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 infor-
mation (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.
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 inter-
est 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 (spl2r01.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 docu-
ment SFF-8485 found at http://www.sffcommittee.com .
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 (C) 2006-2011 Douglas Gilbert
This software is distributed under a FreeBSD license. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
POSE.
SEE ALSO
sg_logs, sg_vpd, sg_ses(sg3_utils); sdparm(sdparm)
smp_utils-0.96 June 2011 SMP_UTILS(8)