What format should I choose for an R-type optical disc with the ability to add files later (multisession)?
I need to record an optical disc (type R) so that I can add files later. This functionality was previously called “multisession.”
In Windows 10 and on websites, the following options are presented, but they are confusing:
- Mastered - a single-session disc, compatible with all drives, but not suitable for adding files later
- LFS (Live File System) - seems to be what I need for multisession
However, I have questions:
- How does LFS allow deleting files from an R-type disc (not RW)?
- How can it work like a USB flash drive if the disc is read-only?
- How is it possible to edit files on a disc that is read-only only?
The problem is compounded by the fact that optical discs are unpopular, so there is little information about multisession recording. I only have one disc available for testing.
Which format should I choose to implement classic “multisession” on an R-type disc?
For R-type (write-once) optical discs with multisession capability, you should choose the LFS (Live File System) format, which is based on UDF (Universal Disk Format). This format allows adding data to new sessions on R-type discs despite their technological limitations.
Table of Contents
- What is multisession on R-type discs
- Comparison of Mastered and LFS formats
- How LFS works with R-discs
- Practical use in Windows 10
- Recommendations and limitations
- Conclusion
What is multisession on R-type discs
Multisession on R-type discs (CD-R, DVD-R) is the ability to add new data to an already recorded disc by creating new sessions. Unlike RW-type discs that can be rewritten, R-discs physically allow each sector to be written only once, but are organized to allow adding new data to free areas.
Technically, this is achieved through:
- Creating a new session with a new data pointer
- Preserving information about previous sessions in the disc directory
- Using a file system that supports incremental writing
Comparison of Mastered and LFS formats
Mastered (ISO 9660)
- How it works: Records all data at once, without the ability to append data
- Compatibility: Maximum - works on all disc drives and devices
- Limitations: Does not support multisession, does not allow changing or deleting files after recording
- File system: ISO 9660 (standard for CD-ROM)
LFS (Live File System)
- How it works: Records data in sessions with the ability to add new data
- Compatibility: Limited - not all older devices can read discs with LFS
- Advantages: Supports multisession, allows managing files like on a USB flash drive
- File system: UDF (Universal Disk Format)
Important: LFS in Windows 10 uses UDF versions 1.50, 2.00, 2.01, or 2.50 for CD-R, DVD±R, and BD-RE discs, depending on the disc type.
How LFS works with R-discs
You may have legitimate questions about how LFS allows “deleting” and “editing” files on read-only discs. The answer lies in the specific implementation of UDF for write-once media:
Virtual file deletion
On R-discs, LFS doesn’t physically delete files - instead:
- Files are marked as deleted in the file system
- Their space becomes unavailable for new recordings
- The file actually remains on the disc but is “hidden” from the user
File editing
Editing is also virtual:
- A new version of the file with changes is created
- The old version is marked as obsolete
- Both versions take up space on the disc
Working like a USB flash drive
Although the disc is physically read-only, LFS creates the illusion of rewriting by:
- Using free areas of the disc for new data
- Organizing the file system with data pointers
- Supporting incremental writing
Technical limitation: As noted in UDF research, for write-once media like R-type discs, “each physical block can be written only once, and writing must occur incrementally”.
Practical use in Windows 10
Choosing LFS format
- Open File Explorer and insert a blank R-type disc
- In the dialog box, select “Create a disc with Live File System”
- Start recording files - they will be saved in the first session
Adding data to new sessions
- Insert a disc with already recorded data
- Windows will recognize the existing structure
- Add new files - they will be recorded in a new session
- Use editing and “deletion” functions as usual
Compatibility
- Modern devices: Read LFS discs without problems
- Older devices: May require special drivers or not support at all
- Game consoles: Usually require Mastered format for compatibility
Recommendations and limitations
When to choose LFS:
- Need to add data to the disc gradually
- Working only with modern devices
- Flexibility in file management is important
LFS limitations:
- Inefficient use of space: “Deleted” files take up space
- Compatibility: Not all devices read LFS
- Reliability: Multisession discs may be less resistant to damage
Alternative: Mastered with multisession
ISO 13490 (extension of ISO 9660) also supports multisession, but:
- Requires special software
- Less convenient for ordinary users
- Better suited for archival purposes
Tip: If you only have one test disc, try recording a small amount of data in LFS first, then add more files in a new session to test functionality.
Conclusion
For implementing classic multisession on R-type optical discs in Windows 10, you should choose the LFS (Live File System) format based on UDF. This format allows:
- Adding data to new sessions on R-discs
- Managing files with familiar operations of copying, moving, and “deleting”
- Using the disc like a USB flash drive, despite technological limitations
Important notes:
- Virtual deletion and editing of files on R-discs is just an illusion - data actually remains on the disc
- Compatibility with other devices may be limited
- For maximum compatibility with outdated equipment, the Mastered format remains preferable
If you have only one test disc, it’s recommended to first experiment with small amounts of data to ensure multisession works on your equipment.