Packet writing is a form of recording information on compact disc that allows information to be written in blocks over a portion of the CD, rather than in a general format using pieces of the entire disc. Without packet writing, some discs may only be capable of being burned with information once, no matter how much available space was still on them. The advantage of packet writing is that it greatly enhances the use of a CD as a storage and file management alternative.
While computer users have always appreciated the fact that CDs have more available space than traditional storage devices such as floppy disks, it has always been a drawback that CDs store information awkwardly, compared to those other formats. CDs were very useful if a great deal of information needed to be stored at once. However, it could be a very expensive storage alternative for users who needed to store a few smaller files a little at a time.
The ability of packet writing to store data on blocks enables more information to be stored on the same CD, even if information has already been written on it. While packet writing does not make all CDs truly rewritable, it may seem like it to the casual observer. The differences, however, while not immediately visible are important and should be noted by those who are accustomed to storing information with traditional floppy disks.
For example, packet writing allows users to "delete" files. However, the files are not truly removed from the disc. Rather, they are just marked as being deleted so they no longer show up on the directory listing.
Likewise, if a file is recorded onto the CD using packet writing, and then a later version is saved, the form saved originally is not actually overwritten. Rather a new copy is saved elsewhere on the disc. The next time a user needs to access that file, it will be the latest version that is loaded.
While these may seem like minor issues, they can become very important. For example, each time an item is saved, there is a little less usable space on the disc. Likewise, deleting an item does not actually free up any space. As long as users keep this in mind while they are working there should not be any surprises.
In some ways, packet writing can be a little deceptive when it comes to deleting files and storing new files. Those who need a greater amount of security for their files may want to think twice about using CDs, as a person with the proper knowledge and equipment may easily be able to retrieve a file that is marked as being deleted. However, packet writing also offers great advantages to those who wish to use CDs to store information. The benefits far outweigh any drawbacks in most cases.