smp_discover - Man Page

invoke DISCOVER SMP function


smp_discover [--adn] [--brief] [--cap] [--dsn] [--help] [--hex] [--ignore] [--interface=PARAMS] [--list] [--multiple] [--my] [--num=NUM] [--phy=ID] [--raw] [--sa=SAS_ADDR] [--summary] [--verbose] [--version] [--zero] SMP_DEVICE[,N]


Sends one or more SAS Serial Management Protocol (SMP) DISCOVER function requests to an SMP target and decodes or outputs the responses. The SMP target is identified by the SMP_DEVICE and the SAS_ADDR. Depending on the interface, the SAS_ADDR may be deduced from the SMP_DEVICE. The mpt interface uses SMP_DEVICE to identify a HBA (an SMP initiator) and needs the additional ,N to differentiate between HBAs if there are multiple present.

If the --phy=ID option is not given then --summary is assumed. When --summary is given or assumed, this utility shows the disposition of each active expander phy in table form. One row is shown for each phy and is described in the Single Line Per Phy Format section below. For this purpose disabled expander phys and those with errors are considered "active" and can be suppressed from the output by adding the --brief option.

Rather than supply options and SMP_DEVICE[,N] on every invocation some can be supplied via environment variables. See the section on Environment Variables below.


Mandatory arguments to long options are mandatory for short options as well.

-A,  --adn

causes the "attached device name" field to be output when the --multiple or --summary option is also given. See the section below on Single Line Per Phy Format. Note the "attached device name" field was added is SAS-2.

-b,  --brief

reduce the decoded response output. If used twice will exit if there is no attached device (after outputting that). When used with --multiple, unattached phys are not listed; when used twice, trims attached phys output.

-c,  --cap

decode and print phy capabilities bits fields (see SNW-3 in draft). Each expander phy has three of these fields: programmed, current and attached. By default these fields are only printed out in hex, or not at all if the --brief option is given or implied. Of the three the attached phy capability field is probably the most interesting. If the --verbose option is given, then the various "G" identifiers are expanded (e.g. instead of "G4:" it prints "G4 (12 Gbps):").

-h,  --help

output the usage message then exit.

-D,  --dsn

outputs the device slot number at the end of each summary line. In summary mode one line is output per expander phy. It is output in the form "dsn=<val>" where <val> is decimal in the range from 0 to 254 inclusive. It is not output if it is not available or has the value 255. An expander typically contains a SES device which yields device slot numbers in its Additional Element Status diagnostic page.

-H,  --hex

output the response (less the CRC field) in hexadecimal.

-i,  --ignore

sets the Ignore Zone Group bit in the SMP Discover request. Expander phys hidden by zoning will appear as "phy vacant" unless this option is given.

-I,  --interface=PARAMS

interface specific parameters. In this case "interface" refers to the path through the operating system to the SMP initiator. See the smp_utils man page for more information.

-l,  --list

list attributes in "name=value" form, one entry per line.

-m,  --multiple

loops over multiple phys within SMP target (typically an expander) and does a DISCOVER request and outputs a one line summary. Phy 0 is queried first, then phy 1, continuing until an error occurs. The starting phy and the number of phys "discovered" can be controlled by --phy=ID and --num=NUM. If --brief is given then there is no output for phys that indicate there is no attached device. When this option is used twice then multi-line output is produced for each phy. See the section below on Single Line Per Phy Format.

-M,  --my

outputs my (this expander's) SAS address in hex (prefixed by "0x"). This is obtained from the DISCOVER response of phy id 0 (unless --phy=ID is given). The expander's SAS address is typically available even if a phy is not connected, "vacant" or disabled. This option overrides most other options (e.g. overrides --multiple and --summary options).

-n,  --num=NUM

number of phys to fetch, starting at --phy=ID when the --multiple option is given. The default value is 0 which is interpreted as "the rest" (i.e. until a "phy does not exist" function result is received). This option is ignored in the absence of the --multiple option.

-p,  --phy=ID

phy identifier. ID is a value between 0 and 254. If this option is not given then the --summary option is assumed.

-r,  --raw

send the response (less the CRC field) to stdout in binary. 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 within 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.

-S,  --summary

output a multi line summary, with one line per active phy. Checks all phys (or less is --num=NUM is given), starting at phy 0 (unless --phy=ID is given). Equivalent to '--multiple --brief' ('-mb'). See the section below on Single Line Per Phy Format. If the --phy=ID is not given then this option is assumed.

-v,  --verbose

increase the verbosity of the output. Can be used multiple times

-V,  --version

print the version string and then exit.

-z,  --zero

zero the Allocated Response Length field in the request. This option also zeros the Request Length field in the request. This is required for strict SAS-1.1 compliance. However this option should not be given in SAS-2 and later; if it is given an abridged response may result.

Single Line Per Phy Format

The --summary option causes SMP DISCOVER responses to be compressed to a header followed by one line per phy. To save space SAS addresses are shown in hex without a '0x' prefix or 'h' suffix. The header line gives the SAS address of the SMP target itself and assumes it is an expander.

Each line starts with "  phy  <n>:" where <n> is the phy identifier (and they are origin zero). That is followed by the routing attribute represented by a single letter which is either "D" for direct routing, "S" for subtractive routing, "T" or "U". Both "T" and "U" imply table routing, the difference is that if REPORT GENERAL indicates "table to table supported" then "U" is output to indicate that phy can be part of an enclosure universal port; otherwise "T" is used. Next comes the negotiated physical link rate which is either "disabled", "reset problem" or "spinup hold". Other states are mapped to "attached". This includes enabled phys with nothing connected which appear as "attached:[0000000000000000:00]".

Information shown between the brackets is for the attached device. Phys that are connected display something like: "attached:[5000c50000520a2a:01 " where the first number is the attached SAS address (in hex) and the second number is the attached device's phy identifier. If the attached device type is other than a SAS or SATA device then one of these abbreviations is output: "exp" (for expander), "fex" (for fanout expander) or "res" (for unknown attached device type). If a phy is flagged as "virtual" then the letter "V" appears next. Next are the protocols supported by the attached device which are shown as "i(<list>)" for initiator protocols and/or "t(<list>)" for target protocols. The <list> is made up of "PORT_SEL", "SSP", "STP", "SMP" and "SATA" with "+" used as a separator. For example a SAS host adapter will most likely appear as: "i(SSP+STP+SMP)". This completes the information about the attached phy, hence the closing right bracket.

If appropriate, the negotiated physical link rate is shown in gigabits per second. Here is an example of a line for expander phy identifier 11 connected to a SATA target (or SATA "device" to use the term):

 phy  11:T:attached:[500605b000000afb:00  t(SATA)]  1.5 Gbps

If the expander has zoning enabled (i.e. REPORT GENERAL response bit for 'zoning enabled' is set) and a phy's zone group is other than zg 1 then the phy's zone group is shown (e.g. "ZG:2").

If the --adn option is given then after the attached SAS address and the attached device's phy identifier are output an extra field is inserted containing the "attached device name" field. For a SAS disk this should be its target device name (in NAA-5 format) and for a SATA disk its WWN (if provided, also in NAA-5 format). Also when the --adn option is given the phy speed and zone group are not output in order to keep the line length reasonable.

If the --dsn option is given and device slot number information is available for the current phy, then "dsn=<num>" is appended to the line. Device slot numbers range from 0 to 254 with 255 meaning there is no corresponding slot so it is not listed.

Environment Variables

If SMP_DEVICE[,N] is not given then the SMP_UTILS_DEVICE environment variable is checked and if present its contents are used instead.

If the SAS address (of the SMP target) is not given and it is required (i.e. it is not implicit in SMP_DEVICE[,N]) 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'.

A device slot number (dsn) is important for establishing the relationship between an expander phy and a SES array element. Newer expanders (e.g. SAS-3) support dsn_s in the DISCOVER (and DISCOVER LIST) functions. These can be shown, if available, with the --dsn option to smp_discover and smp_discover_list utilities.. To ease typing that option often, the SMP_UTILS_DSN environment variableriable, if present, has the same effect.


In SAS-2 and later both the DISCOVER and DISCOVER LIST functions are available. The DISCOVER LIST function should be favoured for several reasons: its response can hold up to 40 descriptors each describing the state of one expander phy. The vast majority of expander chips on the market support 36 phys or less so one DISCOVER LIST response will summarize the states of all its phys. With the DISCOVER function only one expander phy's state is returned in its response. Other advantages of the DISCOVER LIST function are its "phy filter" and "descriptor type" function request fields.


See "Examples" section in

Conforming to

The SMP DISCOVER function was introduced in SAS-1, with small additions in SAS-1.1 . There were a large number of additions in SAS-2 . After SAS-2 the protocol sections of SAS were split into another document series known as the SAS Protocol Layer (SPL) and it was standardized as SPL ANSI INCITS 476-2011. Next came SPL-2 which was standardized as SPL-2 ANSI INCITS 505-2013.  Then came SPL-3 which was standardized as SPL-3 ANSI INCITS 492-2015. SPL-4 is near standardization and its most recent draft is spl4r13.pdf while SPL-5 work has started and its most recent draft is spl5r03.pdf.


Written by Douglas Gilbert.

Reporting Bugs

Report bugs to <dgilbert at interlog dot com>.

See Also

smp_utils, smp_discover_list, smp_phy_control


February 2018 smp_utils-0.99