Schily's USER COMMANDS                                SCGCHECK(1)


     scgcheck - check and validate the ABI of libscg


     scgcheck [ options ]


     Scgcheck is used to check and verify the Application  Binary
     Interface of libscg.

  Device naming
     Most users do not need to care about device naming  at  all,
     as  in  -auto  mode, scgcheck implements auto target support
     and automagically finds a test drive in  case  that  exactly
     one CD-ROM type drive is available in the system.


          Print version information and exit.

          Instead of asking to confirm each  test  before  runing
          it, scgcheck tries to do a fully automated test.

          Set the SCSI target for the device, see notes above.  A
          typical  target device specification is dev=1,6,0 .  If
          a filename must be provided together with the numerical
          target  specification,  the  filename is implementation
          specific.  The correct filename in  this  case  can  be
          found  in  the  system  specific  manuals of the target
          operating system.  On a FreeBSD system without CAM sup-
          port,   you  need  to  use  the  control  device  (e.g.
          /dev/rcd0.ctl).  A correct device specification in this
          case may be dev=/dev/rcd0.ctl:@ .

        General SCSI addressing
          The  target  device  to  the  dev=  option  refers   to
          scsibus/target/lun  of  the  device.  Communication  on
          SunOS is done with the SCSI general driver  scg.  Other
          operating  systems  are  using  a library simulation of
          this    driver.     Possible    syntax    is:      dev=
          scsibus,target,lun  or  dev= target,lun.  In the latter
          case, the device has to be  connected  to  the  default
          SCSI  bus  of the machine.  Scsibus, target and lun are
          integer numbers. Some operating systems or  SCSI  tran-
          sport implementations may require to specify a filename
          in addition.  In this case the correct syntax  for  the
          device  is:   dev=  devicename:scsibus,target,  or dev=

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          devicename:target,lun.  If the name of the device  node
          that  has  been  specified  on  such a system refers to
          exactly one SCSI device, a shorthand in the  form  dev=
          devicename:@  or  dev=  devicename:@,lun  may  be  used
          instead of dev= devicename:scsibus,target,

        Remote SCSI addressing
          To access remote SCSI devices, you need to prepend  the
          SCSI  device  name  by  a  remote device indicator. The
          remote device indicator is either REMOTE:user@host:  or
          REMOTE:host:   A  valid remote SCSI device name may be:
          REMOTE:user@host:  to allow remote SCSI bus scanning or
          REMOTE:user@host:1,0,0  to  access  the  SCSI device at
          host connected to SCSI bus # 1,target  0,  lun  0.   In
          order  to  allow  remote access to a specific host, the
          rscsi(1) program needs to be present and configured  on
          the host.

        Alternate SCSI transports
          ATAPI drives are just SCSI drives that  inherently  use
          the  ATA  packet  interface  as  SCSI command transport
          layer build into the IDE (ATA) transport.  You may need
          to  specify an alternate transport layer on the command
          line if your OS does not implement a  fully  integrated
          kernel driver subsystem that allows to access any drive
          using SCSI commands via a single unique user interface.

          To access SCSI devices via alternate transport  layers,
          you need to prepend the SCSI device name by a transport
          layer indicator.  The transport layer indicator may  be
          something like USCSI: or ATAPI:.  To get a list of sup-
          ported transport layers for  your  platform,  use  dev=

        Portability Background
          To make scgcheck portable to all  UNIX  platforms,  the
          syntax  dev= devicename:scsibus,target, is preferred as
          it hides OS specific knowledge about device names  from
          the  user.  A specific OS may not necessarily support a
          way to specify a real device file name  nor  a  way  to
          specify scsibus,target,lun.

          Scsibus 0 is the default SCSI bus on the machine. Watch
          the  boot  messages  for  more information or look into
          /var/adm/messages for more information about  the  SCSI
          configuration of your machine.  If you have problems to
          figure out what values for scsibus,target,lun should be
          used,  try  the  -scanbus  option of scgcheck described

        Autotarget Mode
          If no dev= option is present, or if it only contains  a

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          transport  specifyer  but no address notation, scgcheck
          tries to scan the SCSI address space for CD-ROM drives.
          If exactly one is found, this is used by default.

          Set  the  default  SCSI  command  timeout  value  to  #
          seconds.   The  default  SCSI  command  timeout  is the
          minimum timeout used for sending SCSI commands.   If  a
          SCSI  command  fails  due  to a timeout, you may try to
          raise  the  default  SCSI  command  timeout  above  the
          timeout  value  of  the failed command.  If the command
          runs correctly with a raised  command  timeout,  please
          report  the  better timeout value and the corresponding
          command to the author of the program.   If  no  timeout
          option  is  present, a default timeout of 40 seconds is

     debug=#, -d
          Set the misc debug value to # (with debug=#) or  incre-
          ment  the  misc  debug  level  by one (with -d). If you
          specify -dd, this equals to debug=2.  This may help  to
          find  problems  while  opening a driver for libscg.  as
          well as with sector  sizes  and  sector  types.   Using
          -debug slows down the process and may be the reason for
          a buffer underrun.

     kdebug=#, kd=#
          Tell the scg-driver to modify the  kernel  debug  value
          while SCSI commands are running.

          A comma separated list of SCSI options that are handled
          by  libscg.   The  implemented  options  may be uptated
          indepentendly  from   applications.    Currently,   one
          option:   ignore-resid  is  supported  to work around a
          Linux kernel bug.

     -silent, -s
          Do not print out a status report for failed  SCSI  com-

     -v   Increment the level of general verbosity by one.   This
          is used e.g. to display the progress of the process.

     -V   Increment the verbose level with respect of  SCSI  com-
          mand  transport  by  one.  This helps to debug problems
          during the process, that occur in the  CD-Recorder.  If
          you  get incomprehensible error messages you should use
          this flag to get more detailed output.  -VV  will  show
          data buffer content in addition.  Using -V or -VV slows
          down the process.

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          Specify the log file to be used instead of check.log.




     cdrecord(1), readcd(1), mkisofs(1), scg(7).


     When using scgcheck  with  the  broken  Linux  SCSI  generic
     driver.  You  should  note  that  scgcheck uses a hack, that
     tries to  emulate  the  functionality  of  the  scg  driver.
     Unfortunately,  the  sg  driver  on Linux has several severe

     o    It cannot see if a SCSI command could not  be  sent  at

     o    It cannot get the SCSI status byte. Scgcheck  for  that
          reason  cannot  report  failing  SCSI  commands in some

     o    It cannot get real DMA count of transfer. Scgcheck can-
          not tell you if there is an DMA residual count.

     o    It cannot get number of bytes valid in auto sense data.
          Scgcheck  cannot  tell you if device transfers no sense
          data at all.

     o    It  fetches  to  few  data  in   auto   request   sense
          (CCS/SCSI-2/SCSI-3 needs >= 18).


     A typical error message for a SCSI command looks like:

          scgcheck: I/O error. test unit ready: scsi sendcmd: no error
          CDB:  00 20 00 00 00 00
          status: 0x2 (CHECK CONDITION)
          Sense Bytes: 70 00 05 00 00 00 00 0A 00 00 00 00 25 00 00 00 00 00
          Sense Key: 0x5 Illegal Request, Segment 0
          Sense Code: 0x25 Qual 0x00 (logical unit not supported) Fru 0x0
          Sense flags: Blk 0 (not valid)
          cmd finished after 0.002s timeout 40s

     The first line gives information about the transport of  the
     command.   The  text  after  the first colon gives the error
     text for the system call from the view  of  the  kernel.  It
     usually  is:   I/O  error  unless other problems happen. The
     next words contain a short description for the SCSI  command

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     that fails. The rest of the line tells you if there were any
     problems for the transport of the command over the SCSI bus.
     fatal  error means that it was not possible to transport the
     command (i.e.  no  device  present  at  the  requested  SCSI

     The second line prints the SCSI command descriptor block for
     the failed command.

     The third line gives information on  the  SCSI  status  code
     returned  by  the  command,  if the transport of the command
     succeeds. This is error information from the SCSI device.

     The fourth line is a hex dump  of  the  auto  request  sense
     information for the command.

     The fifth line is the error text for the sense key if avail-
     able,  followed  by the segment number that is only valid if
     the command was a copy command. If the error message is  not
     directly  related  to the current command, the text deferred
     error is appended.

     The sixth line is the error text for the sense code and  the
     sense  qualifier if available.  If the type of the device is
     known, the sense data is decoded from tables in scsierrs.c .
     The text is followed by the error value for a field replace-
     able unit.

     The seventh line prints the block number that is related  to
     the  failed  command  and  text for several error flags. The
     block number may not be valid.

     The eight line reports the timeout set up for  this  command
     and the time that the command realy needed to complete.





     Joerg Schilling
     Seestr. 110
     D-13353 Berlin

     Additional information can be found on:

     If you have support questions, send them to:

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Schily's USER COMMANDS                                SCGCHECK(1)

     If you have definitely found a bug, send a mail to:

     To subscribe, use:

Joerg SchillingLast change: Version 3.0 2016/01/26              6

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