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- udftools for Debian
- ===================
- Kernel support for packet writing
- ---------------------------------
- Packet writing is a technique by which a writable medium (typically a
- CD or DVD) can be used just like a USB stick or a directory on the
- hard disc: Files and directories can be created/renamed/removed
- freely, and no separate "burning" step is necessary to write the data
- to the medium. Packet writing is possible both with write-once media
- (CD-R, DVD+R, DVD-R) and rewritable media (CD-RW, DVD+RW,
- DVD-RW). Obviously, with write-once media the free space on the
- filesystem will not increase if you delete files.
- In order to do packet writing under Debian Linux, your kernel needs
- both support for UDF (Universal Disc Format) filesystems and for
- packet writing. This is the case for kernels later than about 2.6.10.
- For earlier kernels, you may have to apply patches from Peter
- Osterlund <http://web.telia.com/~u89404340/packet.html>. That site
- also has patches for udftools to make them work with recent kernels -
- they have been applied to this package. This package tries to support
- both old-style packet writing (kernel <2.6.8), and the newer variant
- (>=2.6.10), with and without udev. Use a recent 2.6 kernel for optimal
- results!
- Formatting and using a UDF DVD-RW or CD-RW for packet writing
- -------------------------------------------------------------
- The commands differ depending on whether you are using DVD or CD
- media.
- 1) Edit /etc/default/udftools and add your drive for packet writing.
- For example, if your CD/DVD writer is /dev/hdc and you want it
- available as the default /dev/pktcdvd/0, then use the setting
- "DEVICES=/dev/hdc". Execute "/etc/init.d/udftools start" afterwards to
- register the device.
- If the device name /dev/hdc differs on your system, adjust the
- following commands as appropriate.
- 2) Prepare the medium in restricted overwrite mode:
- DVD-RW: dvd+rw-format -force /dev/hdc
- CD-RW: Do nothing, skip this step!
- 3) Write an empty session spanning the whole medium. It seems that
- without this step, any attempt to create the UDF filesystem will fail.
- DVD-RW: growisofs -Z /dev/hdc=/dev/zero
- CD-RW: cdrwtool -d /dev/hdc -q
- 4) Format the packet device in UDF format.
- DVD-RW: mkudffs --udfrev=0x0150 --spartable=2 --media-type=dvdrw /dev/pktcdvd/0
- CD-RW: mkudffs --udfrev=0x0150 --spartable=2 --media-type=cdrw /dev/pktcdvd/0
- The parameters require some more explanation: For --udfrev, use either
- 0x0150 for UDF version 1.50, or 0x0201 for UDF version 2.01. The
- version decision has mostly to do with compatibility:
- - Windows 98/ME can read up to v1.02
- - Windows 2000, Mac OS 9, Linux 2.4 can read up to v1.50
- - Windows 2003/XP can read up to v2.01
- - Linux 2.6 can read up to v2.60
- For normal data, UDF 1.50 is OK. UDF 2.00 and 2.01 introduce
- additional functionality for streaming audio/video.
- Possible values for --media-type are: hd dvdram dvdrw worm mo cdrw cdr.
- Use the one appropriate for your medium/device.
- 5) Mount the disc. The "noatime" option is important: It will reduce
- the amount of writes to the device and thus increase its lifetime. You
- may first have to create the mount directory using "mkdir
- /media/dvd0":
- mount -t udf -o rw,noatime /dev/pktcdvd/0 /media/dvd0
- The "sync" mount option might also be useful, but will typically cause
- an increased number of write accesses to the medium. From now on, the
- root user can access the filesystem under /media/dvd0 using read and
- write operations.
- 6) If regular users should also have write access, modify the
- permissions as follows _while the filesystem is mounted_:
- chgrp plugdev /media/dvd0 # Set group ownership to "plugdev"
- chmod g+rwx /media/dvd0 # Give full read/write access to group
- Now all users who should have access to the disc need to be added to
- the "plugdev" group using "adduser <username> plugdev".
- To also allow these users to mount and unmount/eject the medium, you
- can use either of these two routes:
- - Install the "pmount" package and add the device to the list of
- allowed devices using "echo /dev/pktcdvd/0 >>/etc/pmount.allow".
- All members of the group "plugdev" will then be able to mount the
- disc using "pmount /dev/pktcdvd/0 dvd0" and unmount it using
- "pumount /media/dvd0".
- - Add a line like the following to /etc/fstab:
- /dev/pktcdvd/0 /media/dvd0 udf rw,noatime,users,noauto 0 0
- This will enable _all_ users to mount the disc using
- "mount /media/dvd0" and unmount it with
- "umount /media/dvd0". However, with the permissions from step 5)
- above, only the members of group "plugdev" ought to be able to
- write to it.
- Support for UDF filesystems
- ---------------------------
- UDF (not packet writing) support in Linux 2.4 and later kernels is
- sufficient to read from and write to UDF filesystems. For example, you
- can create a regular file, "format" it using mkudffs, and then
- loop-mount it. To do this, execute the following commands as root:
- (After "count=", supply the required size in MB of the filesystem.)
- dd if=/dev/zero of=udfimage bs=1M count=10
- mkudffs udfimage
- mkdir udfmnt
- mount -o loop -t udf udfimage udfmnt
- You need Linux 2.4+ with UDF read *and* write support enabled. Now you
- can copy data to the "udfmnt" directory. After an "umount udfmnt", the
- file "udfimage" could theoretically be written to a CD-R(W) or
- DVD-R(W). In practice, you will not want to do that, as the whole
- point of using UDF is to do packet writing.
- -- Richard Atterer <atterer@debian.org> Wed, 22 Nov 2006 23:38:16 +0100
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