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This is the section usually known as "frequently asked
questions with answers". If you have a problem with your partner, kids or
dog, just send it in, as long as it is related to writing CD-Rs or is
otherwise entertaining.
Test it. Use the option -dummy to do an empty run of cdrecord. Do
everything you would do otherwise and watch if the burning process
survives.
If you feed cdrecord directly from mkisofs, then disk intensive processes
such as updating the locate database lower the maximum flow rate
and may corrupt the CD. You better check such processes are not started
via cron , at or anacron while you burn
CD-Rs on older machines.
Fragmentation of files is usually so low that its impact isn't noticed. However,
you can easily construct pathological cases of fragmentation, which lower
the throughput of your hard disks under 100 kbytes/second. So don't do
that. :-)
Yes, files on a hard disk get fragmented over the years. The faster, the
fuller the filesystem is. Always leave 10% or 20% free space, and you
should run fine with respect to writing CD-Rs.
If you're uncertain then look at the messages printed while booting. The
percentage of fragmentation is reported while checking the filesystems. You
can check for this value with the very dangerous command
shell> e2fsck -n /dev/sda5 # '-n' is important!
[stuff deleted -- ignore any errors]
/dev/sda5: 73/12288 files (12.3% non-contiguous)
In this example the fragmentation seems to be very high -- but there are
only 73 very small files on the filesystem. So the
value is not alarming.
There is an experimental utility called e2defrag to defragment extended-2
filesystems. The current version does not work reliable enough to use
it even for private environments. If you really want to defragment your
filesystem, make a backup copy (better: two copies), practice restoring the
data, then create a new filesystem (that will destroy the old) and restore the
data. This sketch is currently the safest technique.
Yes. The only filesystem that isn't reliable and fast enough for writing
CD-ROMs from is the network filesystem (NFS).
I used UMSDOS myself to share the disk-space between Linux and DOS/Win
on a PC (486/66) dedicated for writing CD-ROMs.
Yes. You can put any filesystem you like on the CD. But other operating
systems than Linux won't be able to deal with this CD.
Here goes the recipe:
- Create an empty file of 650MB size.
dd if=/dev/zero of="empty_file" bs=1024k count=650
- Create an extended-2 filesystem on this file
shell> /sbin/mke2fs -b 2048 empty_file
empty_file is not a block special device.
Proceed anyway? (y,n) y
- Mount this empty file through the loopback devices (you need a reasonable new mount for this; read above).
mount -t ext2 -o loop=/dev/loop1 empty_file /mnt
- Copy files to /mnt and umount it afterwards.
- Use
cdrecord on empty_file (which is no
longer empty) as if it were an ISO-9660-image.
If you want to make an entry in /etc/fstab for such
a CD, then disable the checking of the device file on system
startup. For example:
/dev/cdrom /cdrom ext2 defaults,ro 0 0
The first 0 means "don't include in dumps" (backup), the second
(=important) one means "don't check for errors on startup" (fsck would fail
to check the CD for errors).
There are several software packages available. The newest one is
"cdpranoia" and can be downloaded from
http://www.xiph.org/paranoia/
Or you want to try the combination of "cdda2wav" and "sox", available from
sunsite and its mirrors:
ftp://sunsite.unc.edu/pub/Linux/apps/sound/cdrom/cdda2wav0.71.src.tar.gz
ftp://sunsite.unc.edu/pub/Linux/apps/sound/convert/sox-11gamma-cb3.tar.gz
cdda2wav enables you to get a specific interval (or a whole track)
from your audio CD and converts it into a .wav-file. sox converts
the WAV files back into the (audio CD) cdda-format so it can be written to
the CD-R using cdrecord . You don't necessarily need sox if
you use a recent version of cdrecord , because it has built-in
support for .au and .wav files.
The file drivers/scsi/scsi.c contains the information
/*
* Usage: echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi
* with "0 1 2 3" replaced by your "Host Channel Id Lun".
* Consider this feature BETA.
* CAUTION: This is not for hot plugging your peripherals. As
* SCSI was not designed for this you could damage your
* hardware !
* However perhaps it is legal to switch on an
* already connected device. It is perhaps not
* guaranteed this device doesn't corrupt an ongoing data transfer.
*/
Please note that this should only be used if your add SCSI devices to the
end of the chain. Inserting new SCSI devices into an existing chain
disturbs the naming of devices (directory /dev) and may destroy the
complete content of your hard disk.
Some kernel versions do not like re-scanning the SCSI bus at all and your
system may freeze solid when trying out the above. You have been warned.
Yes. But you should be aware of the fact that any errors while reading the
original (due to dust or scratches) will result in a defective copy.
Please note that both methods will fail on audio CDs! You have to use cdrdao or
cdda2wav on audio CDs.
First case: you have a CD-writer and a separate CD-ROM drive. By issuing the
command
cdrecord -v dev=0,6,0 speed=2 -isosize /dev/scd0
you read the data stream from the CD-ROM drive attached as
/dev/scd0 and write it directly to the CD-writer.
Second case: you don't have a separate CD-ROM drive. In this case you have
to use the CD-writer to read out the CD-ROM first:
dd if=/dev/scd0 of=cdimage
This command reads the content of the CD-ROM from the device /dev/scd0 and
writes it into the file "cdimage". The contents of this file are equivalent
to what mkisofs produces, so you can proceed as described earlier
in this document (which is to take the file cdimage as input for cdrecord).
If you want to see a progress-meter and other fancy stuff, then you can also
use Jörg Schillings sdd .
In case you run into errors, then install a recent version of cdrecord,
which ships a tool called "readcd" (found under misc/). It gives you the
same result as dd, but reads sectors on the CD-ROM several times in case
of errors.
Yes. Newer Kernels (2.0.36 and the upcoming 2.2) have built-in support for
the joliet format. Remember you have to use both options in your
/etc/fstab: the keywords iso9660 and joliet (later is really an extension).
For more details, see
http://www-plateau.cs.berkeley.edu/people/chaffee/joliet.html.
Just as you do with regular CD-ROM drives. No tricks at all. Note that you
have to use the scd devices (SCSI CD-ROM) to mount CD-ROMs for reading,
even if you have an ATAPI CD-ROM (remember you configured your
ATAPI devices to act like SCSI). Example entry for /etc/fstab:
/dev/scd0 /cdrom iso9660 ro,user,noauto 0 0
Use bzip2 instead of any other compressor like gzip or
pkzip . It will save you up to 30% of disk-space for larger
(>100kb) files. You can download it from
http://www.muraroa.demon.co.uk/
Instead of writing a true audio CD, you can optionally convert your
WAV audio files into MP3 audio files and store them on a ISO-9660
filesystem as regular files. Usually MPEG III give you a compression of
1:10. Of course, most CD-players are not able to read files... this is the
drawback. On the other hand, why not running the music for your next party
from hard disk? 18 Gbytes are enough for 3000-4000 titles. :-)
A software MPEG III-encoder is available from
http://www.sulaco.org/mp3/
A MPEG III-player is available from
http://www.mpg123.org/
For recorded speech, you may want to try to reduce its size using
shorten or "GSM lossy speech compression":
ftp://svr-ftp.eng.cam.ac.uk/pub/comp.speech/
http://kbs.cs.tu-berlin.de/~jutta/toast.html
You must have an 1.44 MB bootable floppy-disk. Create an exact image of
this floppy-disk by issuing the command
dd if=/dev/fd0 of=boot.img bs=18k
Place this floppy image into the directory holding the collection of your
files (or into a subdirectory of it, just as you like). Tell mkisofs about
this file with the option '-b' and also use '-c'. For details read the file
README.eltorito in the mkisofs-distribution.
An interesting application for a custom bootable CD is as a virus safe DOS-
or Windows-system. It saves you the money for the hard disks (if you have a
network and use samba to put the user-data on a file server). The German
computer magazine c't has a article about this issue in the issue 11/99,
page 206 (
http://www.heise.de/).
Some details about the bootable RedHat CD-ROM is available from
http://members.bellatlantic.net/~smithrod/rhjol-technical.html.
There is an overlay filesystem available for Linux, which is
mounted over the CD-ROM and intercepts all writing operations. New and
modified files are stored elsewhere, but for the user it looks like the
CD-ROM is modified. For more information, see
http://home.att.net/~artnaseef/ovlfs/ovlfs.html.
If that is not enough for your needs: wait for the UDF-filesystem to be
supported by Linux or help developing it (see
http://trylinux.com/projects/udf/. At the moment only reading of
CD-media is supported due to a limitation in the CD-ROM drivers of the
Linux kernel.
Yes. It is reported to work with at least 3 writers at full speed (6x) on a
PC with 233 Mhz and a single SCSI bus running kernel 2.2.12. You need
either a recent version of the Linux kernel (2.2.12 or higher).
Only chapter 2 is Linux-specific. You can apply chapter 3 and 4 even if you
run another family of operating systems than Linux. Please see the files
README.NetBSD, README.aix, README.hpux, README.next,
README.solaris, README.sunos, README.vms or README.xxxBSD from the
cdrecord-distribution.
Probably yes. Compile cdrecord for your platform and issue the command
"cdrecord -scanbus". Read the README.* file for your Unix distributed with
the sources of cdrecord. However, not all variants of Unix can read the
RockRidge, Joliet or HFS extensions on your newly written CD-R.
You have two options. Either you use the built-in configuration file for
cdrecord, or you use a shell wrapper like the one shown below. This
shell script reads a configuration file, which lists the options and
parameters for cdrecord line by line. The names are exactly the same
as on the command line, but without the leading dash. Comments are allowed.
Example:
# be verbose
v
# set the speed of the writer
speed=2
# the device-coordinates in the form BUS,ID,LUN
dev=0,6,0
The configuration files for the wrapper belong into /etc/cdrecord/
and must be referenced on the command line. Example: if you want
to refer to the configuration /etc/cdrecord/mywriter.cfg, then
you can issue the command "cdrecord.sh mywriter.cfg -audio track1...".
Everything after mywrite.cfg is passed to cdrecord.
#! /bin/bash
CFGDIR="/etc/cdrecord"
CFG="$1"
shift
ARGS_LEFT="$@"
if [ ! -f "$CFGDIR/$CFG" ]
then
echo "Configuration file $CFGDIR/$CFG not found. Exiting."
exit 1
fi
while read LINE
do
case $LINE in
\#*|"") continue;;
esac
old_IFS="$IFS"
IFS="$IFS="
set -- $LINE
IFS="$old_IFS"
O_NAME="$1"
O_VALUE=""
while shift
do
case $1 in
"") continue;;
esac
O_VALUE="$1"
done
if [ -z "$O_VALUE" ]
then
O_CDRECORD="$O_CDRECORD -$O_NAME "
continue
fi
O_CDRECORD="$O_CDRECORD $O_NAME=$O_VALUE "
done < "$CFGDIR/$CFG"
set -x #DEBUG
exec cdrecord $O_CDRECORD $ARGS_LEFT
echo "Execution of cdrecord failed."
Somewhere behind the first 32 k on the CD, a block with information about
the CD is located. You can extract the information with the following
shell script:
#! /bin/bash
RD=/dev/cdrom
for i in 32768,7 32776,32 32808,32 32958,128 33086,128 33214,128 \
33342,128 33470,32 33581,16 33598,16 33615,16 33632,16
do
old_IFS="$IFS"
IFS=","
set -- $i
IFS="$old_IFS"
OFFSET=$1
LENGTH=$2
echo "*`dd if=$RD bs=1 skip=$OFFSET count=$LENGTH 2> /dev/null`#"
done
When overwriting CD-RW media, specify the parameter blank=fast to
cdrecord. That's all. See the man page of cdrecord for details about this
parameter.
First of all, the image for a multi-session CD must be formatted using the
ISO-9660 filesystem using RockRidge-extensions. And you must use the option
-multi for cdrecord as long as you want to add further sessions. So at
least for the first session, you must specify the option -multi.
Some CD-writers have no support for CD-ROM XA mode 2 or for session-at-once
(SAO), so you need to specify the switch -data for cdrecord on the command
line.
The images for the second and subsequent sessions are a little bit more
complicated to generate. Mkisofs must know where the free space on the
CD-R begins. That information can be gathered by using the option -msinfo
on cdrecord (see example below).
shell> NEXT_TRACK=`cdrecord -msinfo dev=0,6,0`
shell> echo $NEXT_TRACK
shell> mkisofs -R -o cd_image2 -C $NEXT_TRACK -M /dev/scd5
private_collection/ \
For more information, please read the file README.multi, which is
distributed with cdrecord.
Reported via email: Most CD-writer docs say to use a separate SCSI bus
if going from a CD-ROM to a CD-writer and I have seen this myself in
the following scenario:
Adaptec 2940UW SCSI card, a 24x SCSI CD-ROM and a 4x4 SCSI CD-writer. When
I got the CD-writer, it came with its own ISA SCSI card which could only
handle one device. I figured I'd toss this and use my better adaptec card
for all the stuff. I noticed it was quite prone to buffer under-runs when
recording at the 4x speed, but as soon as I tried hooking up the ISA SCSI
card, it had no problems. I know 2 other people (both using adaptec 2940
cards), who have experienced exactely the same symptoms, usually when writing
from a CD-ROM to a CD-recorder. Though I've never experienced the problem
when going from a hard drive to a CD-writer on the same bus.
Usally a file transfer with FTP is fast enough to feed a CD-recorder at
quadruple (4x) speed even over a 10 Mbit ethernet. You can couple the
ftp-client and cdrecord via a fifo. First create a fifo named cdimage:
mkfifo cdimage
ftp other.host.org
get cdimg cdimage
Then treat cdimage like a regular file, i.e. issue the following command:
cdrecord dev=0,1,0 speed=2 cdimage
Your ftp-client will notice when cdrecord wants to read from the file and
will start transfering data from the ftp-host.
You have to use disk-at-once mode (DAO) to get rid of the cracks.
You can add the setuid-bit to the cdrecord-executable. However, this might
be a security risk. Just setting the permissions on the device files does
not help as cdrecord issues privileged commands via the SCSI generic
interfaces.
which cdrecord
chown root.root /usr/bin/cdrecord
chmod 4111 /usr/bin/cdrecord
You get the printed specifications from Philips and they are expensive.
Here you can find utilities for creation of MPEG videos and Video-CDs:
http://www.mainconcept.de/
http://www.johanni.de/munich-vision/vcd/ Political correct people mention the Berkeley-tools and other
YUV-strategies. Their usage is complicated, takes much time and
harddisk-space and gives you no audio track. I recommend to
use conceptually higher level applications like the ones mentioned
above.
SCSI CD-writers are slightly easier to set up with regard to CD-writing
under Linux. And they are reported to have better error recovery. If that
outweights the higher price cannot be answered generally.
Overburning a CD-R is nothing special. It is at your own risk that the data
fits on the CD-ROM, but thats all. There are no 650 Mbytes-limits in the
software under Linux.
It will finish writing. So you can just couple your favourite backup tool
with cdrecord using a pipe, like in "bru -size=640m -f - | cdrecord
dev=0,1,0 speed=2 -". You have to take special care within the backup
utility if the backup spans multiple CD-Rs.
I know of no way, but anybody is welcome to add this feature to the
Linux kernel sources.
Good question.
A CD-ROM to be read by all systems can only use the plain ISO 9660
format. That means stupid 8+3 filenames from old MS-DOS and without any HFS
(Macintosh), Joliet (Microsoft) or RockRidge (newer Unices) extensions.
There is no extension for longer filenames, which could be read by all
operating systems.
Audio CD-players are only able to deal with audio tracks stored in the first
session. In other words, you cannot add audio tracks using subsequent
sessions. However, writing data tracks into the second session effectively
hides them from audio CD-players. This way you prevent having an silent
track on your mixed mode CD (audio and data mixed).
An answer depends on your wishes. If you need a reason to buy a new
computer, here is the answer from the international association of computer
manufactures: Whatever you plan to do, you need a processor with 800
Mhz. Because it won't fit into your existing motherboard, you need a new
motherboard, too. The easiest solution is just to buy the typical complete
offer as seen in advertisements on TV. Please ignore the rest of this
section.
Now the case if you just want a rational answer: I wrote several CD-ROMs
sucessfully using a "486" with 66 Mhz. Although MS does not consider them
to be PCs anymore, but recommends to run a CE version on them (seen on the
CeBIT), Linux runs even fine on the predecessors of the Pentium and is even
able to write CDs. You can easily find out if the power of your hardware is
sufficient for writing CD-ROMs by testing it out. Just add the command line
switch -dummy when executing cdrecord and the laser will be kept off. Watch
the burning process.
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