SG_LOGS(8)

NAME
sg_logs - access log pages with SCSI LOG SENSE command

SYNOPSIS
sg_logs [--all] [--brief] [--control=PC] [--help] [--hex] [--list] [--maxlen=LEN] [--name] [--page=PG[,SPG]] [--paramp=PP] [--pcb] [--ppc] [--raw] [--reset] [--select] [--sp] [--temperature] [--transport] [--verbose] [--version] DEVICE

sg_logs [-a] [-A] [-b] [-c=PC] [-h] [-H] [-l] [-L] [-m=LEN] [-n] [-p=PG[,SPG]] [-paramp=PP] [-pcb] [-ppc] [-r] [-select] [-sp] [-t] [-T] [-v] [-V] [-?] DEVICE

DESCRIPTION

This utility sends a SCSI LOG SENSE command to the DEVICE and then outputs the response. The LOG SENSE command is used to fetch log pages. Known log pages are decoded by default. When the --reset and/or --select option is given then a SCSI LOG SELECT command is issued to reset parameters.

In SPC-4 revision 5 a subpage code was introduced to both the LOG SENSE and LOG SELECT command. At the same time a page code field was introduced to the to the LOG SELECT command. The log subpage code can range from 0 to 255 (0xff) inclusive. The subpage code value 255 can be thought of as a wildcard.

This utility supports two command line syntaxes, the preferred one is shown first in the synopsis and explained in this section. A later section on the old command line syntax outlines the second group of options.

OPTIONS
Arguments to long options are mandatory for short options as well.

-a, --all
    outputs all the log pages supported by the device. This requires a two stage process: first the "supported log pages" log page is fetched, then for each entry in the response, the corresponding log page is fetched and displayed. When used twice (e.g. '-aa') all log pages and subpages are fetched.

-b, --brief
    shorten the amount of output for some log pages. For example the Tape Alert log page only outputs parameters whose flags are set when --brief is given.

-c, --control=PC
    accepts 0, 1, 2 or 3 for the PC argument:
      0 : current threshold values
      1 : current cumulative values
      2 : default threshold values
      3 : default cumulative values
    The default value is 1 (i.e. current cumulative values).

-h, --help
    print out the usage message then exit.

-H, --hex
    The default action is to decode known mode page numbers (and subpage numbers) into text. When this option is used once, the response is output in hexadecimal.

-l, --list
    lists the names of all logs sense pages supported by this device. This is done by reading the "supported log pages" log page. When used twice (e.g. '-ll') lists the names of all logs sense pages and subpages supported by this device. There is a list of common log page codes below.

-m, --maxlen=LEN
    sets the "allocation length" field in the LOG SENSE cdb. The is the maximum length in bytes that the response will be. Without this option (or LEN equal to 0) this utility first fetches the 4 byte response then does a second access with the length indicated in the first (4 byte) response. Negative values and 1 for LEN are not accepted. Responses can be quite large (e.g. the background scan results log page) and this option can be used to limit the amount of information returned.

-n, --name
    decode some log pages into 'name=value' entries, one per line. The name contains no space and may be abbreviated and the value is decimal unless prefixed by '0x'. Nesting is indicated by leading spaces. This form is meant to be relatively easy to parse.

-O, --old
    switch to older style options.

-p, --page=PG[,SPG]
    log page code to access. PG is expected to be a decimal number between 0 and 63 inclusive. A hexadecimal number can be specified by a leading "0x" or a trailing "h". Common log page codes are listed below. Optionally SPG, a subpage code, can be given. SPG is expected to be a decimal number between 0 and 255 inclusive.

-P, --paramp=PP
    PP is the parameter pointer value to place in a field of that name in the LOG SENSE cdb. A decimal number in the range 0 to 65535 (0xffff) is expected. When a value greater than 0 is given the --ppc option should be selected. The default value is 0.

-q, --pcb
    show Parameter Control Byte settings (only relevant when log parameters being output in ASCII).

-Q, --ppc
    sets the Parameter Pointer Control (PPC) bit in the LOG SENSE cdb. Default is 0 (i.e. cleared).

-r, --raw
    output the response in binary to stdout. Error messages and warnings are output to stderr.

-R, --reset
    use SCSI LOG SELECT command (PCR bit set) to reset the all log pages (or the given page). [SPC-4 (rev 6) doesn't say that a given log (sub)page can be reset yet.] Exactly what is reset depends on the accompanying SP bit (i.e. --sp option which defaults to 0) and the PC ("page control") value (which defaults to 1). Supplying this option implies the --select option as well. This option seems to clear error counter log pages but leaves pages like self-test results, start-stop cycle counter and temperature log pages unaffected. This option may be required to clear log pages if a counter reaches its maximum value since the log page in which the counter is found will remain "stuck" until something is done.

-S, --select
    use a LOG SELECT command. The default action (i.e. when neither this option nor --reset is given) is to do a LOG SENSE command. When this option is given, the SP bit (i.e. --sp option which defaults to 0), the PC ("page control") value (which defaults to 1) and the PCR bit (i.e. --reset option which defaults to 0) are placed in the LOG SELECT cdb. At some stage the log page and subpage options may also be active [but SPC-4 (rev 6) doesn't say that].

-s, --sp
    sets the Saving Parameters (SP) bit. Default is 0 (i.e. cleared). When set this instructs the device to store the current log page parameters (as indicated by the DS and TSD parameter codes) in some non-volatile location. Hence the log parameters will be preserved across power cycles. This option is typically not needed, especially if the GLTSD flag is clear in the control mode page as this instructs the device to periodically save all saveable log parameters to non-volatile locations.

-t, --temperature
    outputs the temperature. First looks in the temperature log page and if that is not available tries the Informational Exceptions log page which may also have the current temperature (especially on older disks).

-T, --transport
    outputs the transport ('Protocol specific port') log page. Equivalent to setting '--page=18h'.

-v, --verbose
    increase level of verbosity.

-V, --version
    print out version string then exit.

NOTES
This utility will usually do a double fetch of log pages with the SCSI LOG SENSE command. The first fetch requests a 4 byte response (i.e. place 4 in the "allocation length" field in the cdb). From that response it can calculate the actual length of the response which is what it asks for on the second fetch. This is typical practice in SCSI and guaranteed to work in the standards. However some older devices don't comply. For those devices using the --maxlen=LEN option will do a single fetch. A value of 252 should be a safe starting point.

Various log pages hold information error rates, device temperature, start stop cycles since device produced and the results of the last 20 self tests. Self tests can be initiated by the sg_senddiag(8) utility. The smartmontools package provides much of the information found with sg_logs in a form suitable for monitoring the health of SCSI disks and tape drives.

Here is a list of log pages that are decoded by this utility. [The code values can be given to '--page=' as is, with a trailing "h" instead of the leading "0x", or as their decimal equivalents.]:

0x0 Supported log pages
0x0,0xff Supported log pages and subpages
0x1 Buffer overrun/underrun
0x2 Write error counter
0x3 Read error counter
0x4 Read reverse error counter
0x5 Verify error counter
0x6 Non-medium error
0x7 Last n error events
0x8 Format status (sbc-2)
0xb Last n deferred errors or asynchronous events
0xc Sequential access device (ssc-2)
0xd Temperature
0xe Start-stop cycle counter
0x10 Self-test results
0x15 Background scan results (sbc-3)
0x17 Non-volatile cache (sbc-3)
0x18 Protocol specific port (SAS transport)
0x19 General statistics and performance
0x2f Informational exceptions
0x37 Seagate cache (vendor, disk)
0x3e Seagate factory (vendor, disk)

In the 2.4 series of Linux kernels the DEVICE must be a SCSI generic (sg) device. In the 2.6 series block devices (e.g. SCSI disks and DVD drives) can also be specified. For example "sg_logs -a /dev/sda" will work in the 2.6 series kernels.

EXIT STATUS
The exit status of sg_logs is 0 when it is successful. Otherwise see the sg3_utils(8) man page.

OLDER COMMAND LINE OPTIONS
The options in this section were the only ones available prior to sg3_utils version 1.23 . In sg3_utils version 1.23 and later these older options can be selected by either setting the SG3_UTILS_OLD_OPTS environment variable or using '--old' (or '-O) as the first option.

Options with arguments or with two or more letters can have an extra '-' prepended. For example: both '-pcb' and '--pcb' are acceptable.

-a  outputs all the log pages supported by the device. Equivalent to --all in the main description.

-A  outputs all the log pages and subpages supported by the device. Equivalent to '--all --all' in the main description.

-c=PC
    Equivalent to --control=PC in the main description.

-h  suppresses decoding of known log sense pages and prints out the response in hex instead.

-H  same action as '-h' in this section and equivalent to --hex in the main description.

-l  lists the names of all logs sense pages supported by this device. Equivalent to --list in the main description.

-L  lists the names of all logs sense pages and subpages supported by this device. Equivalent to '--list --list' in the main description.

-m=LEN
    request only LEN bytes of response data. Default is 0 which is interpreted as all that is available. LEN is decimal unless it has a leading '0x' or trailing 'h'. Equivalent to --maxlen=LEN in the main description.

-n  Equivalent to --name in the main description.

-N  switch to the newer style options.

-p=PG[,SPG]
    PG is the log page code to access. Should be a hexadecimal number between 0 and 3f inclusive. If given SPG is the log subpage code. SPG should be a hexadecimal number between 0 and ff inclusive. The subpage code of 'ff' can be thought of as a wildcard.

-paramp=PP
    PP is the parameter pointer value (in hex) to place in command. Should be a number between 0 and ffff inclusive.

-pcb
    show Parameter Control Byte settings (only relevant when log parameters being output in ASCII).

-ppc
    sets the Parameter Pointer Control (PPC) bit. Default is 0 (i.e. cleared).

-r  use SCSI LOG SELECT command (PCR bit set) to reset the all log pages (or the given page). Equivalent to --reset in the main description.

-select
    use a LOG SELECT command. Equivalent to --select in the main description.

-sp sets the Saving Parameters (SP) bit. Default is 0 (i.e. cleared). Equivalent to --sp in the main description.

-t  outputs the temperature. Equivalent to --temperature in the main description.

-T  outputs the transport ('Protocol specific port') log page. Equivalent to --transport in the main description.

-v  increase level of verbosity.

-V  print out version string then exit.

-?  output usage message then exit.

AUTHOR
Written by Doug Gilbert

REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.

COPYRIGHT
Copyright © 2002-2007 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.

SEE ALSO
smartctl(smartmontools), sg_senddiag(8)