Packet-Writing

Packet writing is a technique for writing ( 'burning' ) to optical media in a way, as is common on hard drives or floppy disks. This is also referred to as " incremental writing ."

Technology

Normally, optical media can, such as CD -R ( W) and DVD ± R ( W), can only be described in one piece ( Disc-At -Once, Track-At -Once and Session-At - Once).

Under the English term " packet writing " refers to a technique for incremental writing to media. This makes it possible to use optical media such as a hard disk or a floppy disk., Files can be copied to the respective optical medium, moved, changed, renamed or deleted.

Mostly comes for packet writing the " Universal Disk Format" ( UDF) version 1.50 from the file system used. UDF is best adapted to the requirements of optical media and therefore the recommended file system on all optical media incrementally described.

In order to use packet writing, you need a CD / DVD drive that supports writing data in small units to the media. As good as all CD and DVD burners support this feature, but it could be that it is missing, especially on older devices.

UDF

UDF stands for " Universal Disk Format ", and describes the file system (or high- level format ), in which the data or file is being written to the media. UDF was thereby developed with particular emphasis on optical storage media.

For an optical medium each write is a burden. Various optical media hold a different number of such loads, and this at any point of the entire memory area. To maintain the life of the medium as high as possible, it is therefore necessary to burden it as evenly as possible.

For use with packet writing the Universal Disk Format in Version 1.50 or higher is required. UDF version 1.02 is a static file system, similar to ISO 9660, which is used for example as " ISO / UDF bridge " for DVD-Video for use.

One of the most usual loads when writing to optical media is updating the table of contents dar. Every time a file changes, if only the file name, this change must be written to the table of contents. UDF Version 1.50 is so so good for packet writing suitable because it stores the table of contents at various points on the optical medium and thus distributes the load.

Another problem is the management of free space on hard drives dar. files are quickly written where otherwise no file - in other words, where, for example, just a file was deleted and now is free memory again. In optical media, but this would mean that already loaded ( as described ) storage area loaded again ( as described again ) is. UDF versions 1.50 and above, therefore, result in a list of areas that have already been described and how often they have been described. When a new file is stored in such a UDF file system, this is done so at a location that is not or not so often charged, the total load of the optical medium is thus kept approximately the same at all points.

Furthermore UDF provides a defect management, the ( overloaded, damaged ) portions of the originally available memory fades already consumed. Despite these unusual areas, the optical medium can be used. However, the use of this defect management is dependent on the software that implements the UDF file system.

Warning: Deleted or overwritten files are initially marked with UDF only the table of contents as deleted. This is true even if the file was deleted with special " eraser software ". The reconstruction of recently deleted files is possible with relatively little effort. Would it be absolutely necessary to delete a file physically from the respective medium, one would have to overwrite the entire memory area with new data, or used the Eraser program can deal with the peculiarities of the UDF file system.

In write-once media (CD -R and DVD ± R), it is not possible for technical reasons, already written to delete or overwrite. Therefore, the medium once it is full, only be read, but not described. Deleted on such media files are always relatively easy to reconstruct.

Important: Rewritable media can only guarantee a certain number of write accesses. Only the UDF file system to version 1.50 or later loaded the medium evenly, so that these writes do not ruin the medium prematurely.

Packet writing is not UDF

Often no distinction is made between UDF and packet-writing. Since this can lead to considerable confusion should be clarified in the following, such as packet writing interacts with UDF, but also what the two substantially different.

What is UDF and what is its use?

  • UDF is a file system such as FAT32, NTFS, or ext3.
  • A storage medium, a partition or similar (such as a loop device or virtual disk ) can be formatted with UDF. Theoretically, it is also possible to format a partition on the hard drive with UDF. Although this is practically feasible, it is often confounded by the support from the operating system.
  • UDF is available in different versions. However, the difference between UDF 1.02 and UDF 1.50 is so large, such as the difference between FAT32 (as in Windows 98/Me) and NTFS ( as in Windows 2000/XP).
  • UDF is an ISO standard and is therefore supported by many operating systems, at least partially. Most operating systems can read UDF in versions 1.02, 1.50 and / or 2.01. Some operating systems can also write UDF ( ≙ full UDF support ).

What is packet writing and how is it used?

  • As packet-writing refers to a technique to describe optical media in units of small packets, hence the name "Packet " - small packets, and " Writing" - describe ( to the optical media burning ).
  • Packet writing is only possible with suitable hardware. However, as good as any modern CD and DVD drives, these hardware support.
  • Packet writing is understood here as a driver, such as an ATAPI driver that provides access to an ATAPI CD - ROM drive. The packet writing driver enables access to the medium in the described manner: small packets can be read and written, similar to the hard disk sectors can be read and written. This means that packet writing works independently of the file system used. One can therefore format a medium which was included on the packet writing driver in an operating system with any file system. In practice, however, this is not very advisable in some operating systems even the packet writing driver prevents use of other file systems as UDF.
  • For example, you could put NTFS on an optical medium, therefore even. However, this is strongly discouraged, as the lifetime of the medium would be reduced. This is partly because NTFS is a journalized file system and initiated many write accesses for each file operation which would in extreme conditions an optical medium. The same applies, for example, ext3, and all other journaled file systems because they are designed primarily for hard drives.
  • Simple file systems such as FAT, FAT32 or ext2 ( with the noatime mount option ) charge an optical medium is limited, but always write the table of contents at the same location. These file systems are therefore only suitable for packet writing and visual media, but can in exceptional cases (eg for compatibility with older operating systems which are not yet supported UDF ) quite apply. Generally this is not recommended by these file systems, since here also the life of the optical medium with each write access drops drastically.
  • The packet writing driver utilizes means CD-/DVD-Hardware-Treiber to the drive,
  • During the UDF driver, who is a file system driver, accessing the drive using packet writing driver.

Software

To use packet writing, you need either a driver or packet writing program. These represent only the packet-writing function in the operating system or the user. To use the conventional UDF system, it additionally needs a UDF driver. In some operating systems, these two functions ( packet-writing and UDF ) can be realized in a single driver. Packet-writing programs integrate both functions in a program.

Is the operating system and are prepared, for example, installed the drivers, optical media can be formatted first, then be like a hard drive used in the normal operating system way.

Following is a partial list of drivers and packet-writing programs for different operating systems.

GNU / Linux

  • Pktcdvd is integrated into the latest Linux kernel version 2.6
  • Udffs is integrated in Linux kernel 2.4

Mac OS

  • SAI WriteUDF! UDF Writer for Mac OS (Software Architects, Inc. )

Windows

  • DLA: Drive Letter Access (Sonic Solutions)
  • Drag-to- Disc, formerly DirectCD ( Roxio, Adaptec earlier )
  • DVD Write Now - Freeware
  • Nero InCD (Nero AG, formerly Ahead )
  • SAI WriteDVD! and ReadDVD! (Software Architects, Inc. )
  • From Windows Vista integrated under the name Live File System

Embedded

  • TinyUDF (Storage Labs B. V. )

FREE " UDF reader " programs that only allow reading of UDF file systems:

  • B 's CLiP UDF Reader / MRW remapper, Version 5.02 Reading support to UDF version 1.50 for Windows 95 OSR2/98/Me
  • B 's CLiP UDF Reader NT, Version 1.00 Reading support to UDF version 1.50 for Windows NT 4.0 SP6
  • Nero InCD Reader, version 5: Reading support to UDF 2.60 for Windows 2000/XP/2003/Vista (32 -bit) and version 4: Reading support to UDF version 2.60 for Windows 98/Me/2000/XP/2003
  • Veritas DLA UDF Reader, version 2:55 IBM ( MIGR - 42199 ) Reading support ( UDF version unknown) for Windows 95/98/98SE/Me/NT/2000/XP Download the "File link" the file b91z06us.exe with the description " Veritas DLA UDF reader ( German ) ".
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