SCGCHECK

Section: Schily\'s USER COMMANDS (1)
Updated: Version 2.0
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NAME

scgcheck - check and validate the ABI of libscg

SYNOPSIS

scgcheck [ options ]

DESCRIPTION

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

The device refers to scsibus/target/lun of the drive. 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 drive has to be connected to the default SCSI bus of the machine. Scsibus, target and lun are integer numbers. Some operating systems or SCSI transport implementations may require to specify a filename in addition. In this case the correct syntax for the device is: dev= devicename:scsibus,target,lun or dev= 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,lun.

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 .BIREMOTE: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.

To make readcd portable to all UNIX platforms, the syntax dev= devicename:scsibus,target,lun is preferred as is hides OS specific knowledge about device names from the user. A specific OS must 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 cdrecord.

OPTIONS

-version

Print version information and exit.

dev=target

Sets the SCSI target default for SCSI Bus scanning test, see notes above. This allows e.g. to specify to use Solaris USCSI or remote SCSI for the bus scanning case.

For the non bus scanning case, a typical device specification is dev=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 support, 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:@ .

On Linux, drives connected to a parallel port adapter are mapped to a virtual SCSI bus. Different adapters are mapped to different targets on this virtual SCSI bus.

If no dev option is present, cdrecord will try to get the device from the CDR_DEVICE environment.

If the argument to the dev= option does not contain the characters ',', '/', '@' or ':', it is interpreted as an label name that may be found in the file /etc/default/cdrecord (see FILES section).

timeout=#

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 used.

debug=#, -d

Set the misc debug value to # (with debug=#) or increment 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.

-silent, -s

Do not print out a status report for failed SCSI commands.

-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 command 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.

f=file

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

EXAMPLES

FILES

NOTES

When using scgckeck 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 bugs:

*: It cannot see if a SCSI command could not be sent at all.
*: It cannot get the SCSI status byte. Scgcheck for that reason cannot report failing SCSI commands in some situations.
*: It cannot get real DMA count of transfer. Scgcheck cannot tell you if there is an DMA residual count.
*: It cannot get number of bytes valid in auto sense data. Scgcheck cannot tell you if device transfers no sense data at all.
*: It fetches to few data in auto request sense (CCS/SCSI-2/SCSI-3 needs >= 18).

DIAGNOSTICS

A typical error message for a SCSI command looks like:

readcd: 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 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 address).

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 available, 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 replaceable 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.

BUGS

CREDITS

MAILING LISTS

AUTHOR

Joerg Schilling
Seestr. 110
D-13353 Berlin
Germany

Additional information can be found on:
http://www.fokus.fhg.de/usr/schilling/cdrecord.html

If you have support questions, send them to:

[email protected]
or [email protected]

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