If you have data on this media, you are out of luck. Done automatically every night. Before you remove your data, verify with Dave to be sure that it has been backed up successfully. Random access means that access to stored data can be anywhere on the media. The advantage of this type of access is that it is relatively fast as compared to sequential access.
Sequential access means that each file is laid sequentially on the media.
This type of access is normally slower than the random access mentioned above. A media is appendable if you can add more data to an already written media. Single-session mode means that once the CD is written to, the disk's table of content is closed and no more writing is possible. Appending is not possible in this mode. Multi-session modes means that after the initial write, the disk's table of content is kept open and you can write to the disk again.