SCGCHECK(1) Schily's USER COMMANDS SCGCHECK(1)NAMEscgcheck - check and validate the ABI of libscg
SYNOPSISscgcheck [ 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. Com-
munication on SunOS is done with the SCSI general driver
scg. Other operating systems are using a library simula-
tion of this driver. Possible syntax is: dev= scsi-
bus,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= device-
name: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 short-
hand in the form dev= devicename:@ or dev= device-
name:@,lun may be used instead of dev= devicename:scsi-
bus,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
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.
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 scsi-
bus,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 con-
figuration of your machine. If you have problems to fig-
ure 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 speci-
fication, 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 inter-
preted 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 com-
mand runs correctly with a raised command timeout,
please report the better timeout value and the cor-
responding 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 pro-
cess.
f=file Specify the log file to be used instead of
check.log.
EXAMPLESFILESSEE ALSOcdrecord(1), readcd(1), mkisofs(1), scg(7).
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:
o It cannot see if a SCSI command could not be sent
at all.
o It cannot get the SCSI status byte. Scgcheck for
that reason cannot report failing SCSI commands in
some situations.
o It cannot get real DMA count of transfer. Scgcheck
cannot 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).
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 ker-
nel. It usually is: I/O error unless other problems hap-
pen. 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 pos-
sible 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 mes-
sage 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.
BUGSCREDITSMAILING LISTSAUTHOR
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:
cdrecord-support@berlios.de
or other-cdwrite@lists.debian.org
Of you have definitely found a bug, send a mail to:
cdrecord-developers@berlios.de
or schilling@fokus.fhg.de
To subscribe, use:
http://lists.berlios.de/mailman/listinfo/cdrecord-develop-
ers
or http://lists.berlios.de/mailman/listinfo/cdrecord-sup-
port
Joerg Schilling Version 2.0 SCGCHECK(1)
