Archiving is the process of moving recorded video data from the live media volume to the archive media volume. These should always be separate media.
The archive process serves a few purposes.
1. It allows for defragmentation of the video files.
2. It allows for the use of much slower recording media for long term "archive" storage.
3. Some VMS' allow you to archive to multiple destinations for redundancy of data.
4. Some VMS' allow for archive encryption.
5. Some VMS' allow the archive to have a lower frame rate than the live data. This is a great storage space saver for long term archives.
If you use a live / archive process, and you have multiple small volumes, you should set the archiving process to use dynamic archive path. This will allow you to take maximum advantage of the multiple small volumes you have available to store your archive data.