readom - read or write data Compact Discs
readom dev=device [ options ]
Readom is used to read or write Compact Discs.
The device refers to a device location similar to the one
used in the wodim command. Refer to its manpage for details.
Also note that this version of readom uses a modified libusal
library which has a different behaviour compared to the one distributed by
its original author.
If no options except the dev= option have been specified, readom
goes into interactive mode. Select a primary function and then follow the
instructions.
- -version
- Print version information and exit.
- dev=target
- Sets the SCSI target for the drive, see notes above. 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, readom 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/wodim.conf (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 libusal. 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 usal-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 filename where the output should be written or the input
should be taken from. Using '-' as filename will cause readom to
use stdout resp. stdin.
- -w
- Switch to write mode. If this option is not present, readom reads
from the specified device.
- -c2scan
- Scans the whole CD or the range specified by the
sectors=range for C2 errors. C2 errors are errors that are
uncorrectable after the second stage of the 24/28 + 28/32 Reed Solomon
correction system at audio level (2352 bytes sector size). If an audio CD
has C2 errors, interpolation is needed to hide the errors. If a data CD
has C2 errors, these errors are in most cases corrected by the ECC/EDC
code that makes 2352 bytes out of 2048 data bytes. The ECC/EDC code should
be able to correct about 100 C2 error bytes per sector.
If you find C2 errors you may want to reduce the speed using
the speed= option as C2 errors may be a result of dynamic
unbalance on the medium.
- -scanbus
- Scan all SCSI devices on all SCSI busses and print the inquiry strings.
This option may be used to find SCSI address of the devices on a system.
The numbers printed out as labels are computed by: bus * 100 +
target
- sectors=range
- Specify a sector range that should be read. The range is specified by the
starting sector number, a minus sign and the ending sector number. The end
sector is not included in the list, so sectors=0-0 will not read
anything and may be used to check for a CD in the drive.
- speed=#
- Set the speed factor of the read or write process to #. # is an integer,
representing a multiple of the audio speed. This is about 150 KB/s for
CD-ROM and about 172 KB/s for CD-Audio. If no speed option is
present, readom will use maximum speed. Only MMC compliant drives
will benefit from this option. The speed of non MMC drives is not changed.
Using a lower speed may increase the readability of a CD or
DVD.
- ts=#
- Set the maximum transfer size for a single SCSI command to #. The syntax
for the ts= option is the same as for wodim fs=# or sdd bs=#.
If no ts= option has been specified, readom
defaults to a transfer size of 256 kB. If libusal gets lower values from
the operating system, the value is reduced to the maximum value that is
possible with the current operating system. Sometimes, it may help to
further reduce the transfer size or to enhance it, but note that it may
take a long time to find a better value by experimenting with the
ts= option.
- -notrunc
- Do not truncate the output file when opening it.
- -fulltoc
- Retrieve a full TOC from the current disk and print it in hex.
- -clone
- Do a clone read. Read the CD with all sub-channel data and a full TOC. The
full TOC data will be put into a file with similar name as with the
f= option but the suffix .toc added.
- -noerror
- Do not abort if the high level error checking in readom found an
uncorrectable error in the data stream.
- -nocorr
- Switch the drive into a mode where it ignores read errors in data sectors
that are a result of uncorrectable ECC/EDC errors before reading. If
readom completes, the error recovery mode of the drive is switched
back to the remembered old mode.
- retries=#
- Set the retry count for high level retries in readom to #.
The default is to do 128 retries which may be too much if you like to read
a CD with many unreadable sectors.
- -overhead
- Meter the SCSI command overhead time. This is done by executing several
commands 1000 times and printing the total time used. If you divide the
displayed times by 1000, you get the average overhead time for a single
command.
- meshpoints=#
- Print read-speed at # locations. The purpose of this option is to create a
list of read speed values suitable for e.g. gnuplot. The speed
values are calculated assuming that 1000 bytes are one kilobyte as
documented in the SCSI standard. The output data created for this purpose
is written to stdout.
- -factor
- Output the speed values for meshpoints=# as factor based on
single speed of the current medium. This only works if
readom is able to determine the current medium type.
For all examples below, it will be assumed that the drive is connected to the
primary SCSI bus of the machine. The SCSI target id is set to 2.
To read the complete media from a CD-ROM writing the data to the
file cdimage.raw:
readom dev=2,0 f=cdimage.raw
To read sectors from range 150 ... 10000 from a CD-ROM writing the
data to the file cdimage.raw:
readom dev=2,0 sectors=150-10000 f=cdimage.raw
To write the data from the file cdimage.raw (e.g. a
filesystem image from genisoimage) to a DVD-RAM, call:
readom dev=2,0 -w f=cdimage.raw
- RSH
- If the RSH environment is present, the remote connection will not
be created via rcmd(3) but by calling the program pointed to by
RSH. Use e.g. RSH=/usr/bin/ssh to create a secure shell
connection.
Note that this forces wodim to create a pipe to the
rsh(1) program and disallows wodim to directly access the
network socket to the remote server. This makes it impossible to set up
performance parameters and slows down the connection compared to a
root initiated rcmd(3) connection.
- RSCSI
- If the RSCSI environment is present, the remote SCSI server will
not be the program /opt/schily/sbin/rscsi but the program pointed
to by RSCSI. Note that the remote SCSI server program name will be
ignored if you log in using an account that has been created with a remote
SCSI server program as login shell.
wodim(1), genisoimage(1), rcmd(3), ssh(1).
Unless you want to risk getting problems, readom should be run as root.
If you don't want to allow users to become root on your system, readom
may safely be installed suid root. For more information see the additional
notes of your system/program distribution or README.suidroot which is part of
the Cdrkit source.
Documentation of the wodim program contains more technical
details which could also apply to readom.
A typical error message for a SCSI command looks like:
readom: 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 really needed to complete.
The readom program described here is the Cdrkit spinoff from the original
readcd application (see AUTHOR section for details). It may contain
bugs not present in the original implementation.
It is definitely less portable than the original
implementation.
For platform specific bugs, see the corresponding README.platform
file in the Cdrkit documentation (eg. README.linux).
If you want to actively take part on the development of readom, you may join the
developer mailing list via this URL:
http://alioth.debian.org/mail/?group_id=31006
The mail address of the list is:
debburn-devel@lists.alioth.debian.org
Joerg Schilling
Seestr. 110
D-13353 Berlin
Germany
This is application is a spinoff from the original implementation
of readcd delivered in the cdrtools package [1] created by Joerg Schilling,
who deserves the most credits for its success. However, he is not involved
into the development of this spinoff and therefore he shall not be made
responsible for any problem caused by it. Do not try to get support from the
original author!
Additional information can be found on:
https://alioth.debian.org/projects/debburn/
If you have support questions, send them to
debburn-devel@lists.alioth.debian.org
If you have definitely found a bug, send a mail to this list or
to
submit@bugs.debian.org
writing at least a short description into the Subject and
"Package: cdrkit" into the first line of the mail body.
[1] Cdrtools 2.01.01a08 from May 2006, http://cdrecord.berlios.de