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CD Recording FAQ
3. Basic notions
3.3. Packet writing
The only way of using a cd-r(w) disc as a giant floppy is by utilizing packet writing. In this way, you can add files to a cd without the fear of buffer underrun, and even save files on a cd as you would with a Zip drive or another hard disk.
In order to achieve this, you must install proper drivers. Since UDF is the file system of choice for packet writing, you must install UDF software, which will provide the necessary options. The main disadvantage of UDF software is that it tends to interfere with other programs and cause serious compatibility problems. Almost always packet writing programs require that the Auto Insert Notification for the recorder is ON.
First of all, before writing anything on a cd you have to format it. In this way, it will be ready to be used for packet writing. A full format for a cd-rw disc takes some time depending on the speed of the recorder. CD-R media are formatted within seconds.
Next, you can begin using the cd till you fill it. When this happens, you can finalize the cd, which means that you will be able to read it on any computer as if it were a usual data cd. Finalizing the cd is strongly advised.
While using the recorder for packet writing, you will notice that the overal speed is very low. Response times are very irritating and you may discover that writing a few kilobytes now and then can be a serious delay for your work.
3.3.1. Packet writing on CD-R and CD-RW media
Under packet writing, cd-r and cd-rw media behave differently:
- CD-R media utilize variable length packets, which means a capacity of about 620MB for a 74min cd. If you erase a file (or overwrite it), you don't regain cd space, since the surface of cd-r media can't be re-formatted.
- CD-RW media utilize fixed length packets, which means a capacity of about 520MB for a 74min cd. You can erase a file and regain free space on the cd. You can also use cd-rw media like cd-r media (with variable length packets), which offers faster speeds, especially if the recorder is equipped with a large buffer memory.
In general, using cd-r media offers more in terms of speed and maximum capacity, but may result to greater expenses since you can't reuse the disc.
3.3.2. Packet writing reliability
Despite being an easy way to use a recorder, packet writing suffers in terms of reliability.
First of all, a udf formatted cd needs a proper driver in order to read it on another system. Since there are so many programs for packet writing, there is an equal number of drivers which must be installed in order to read a cd written with packet writing. Even different versions of the same packet writing software may not be compatible with each other. This means that, till finalizing to ISO, a cd used with packet writing is not suitable for long term storage.
Even worse, till finalizing to ISO all data on the cd are prone to loss. The reason for this is that if, for any reason, the writing process at one point fails, all data will be inaccessible. Often you can retrieve data using proper data recovery software, but there are cases where the cd won't even be recognized by any drive.
Such incidents are not rare. On the contrary, it is only a matter of time for users of packet writing to experience such failures, which are inherent to the nature of packet writing.
Though packet writing sounds appealing and many people find it the ideal way to use their recorder, the serious drawback of lower reliability cannot be overlooked. It is strongly advised to avoid using packet writing for sensitive data you can't afford to lose!