Formatting A CD-R with live file system not working.

[Ajfer03]

Hey everyone, I recently put some software onto a CD-R I had. I used live file system on the disc and put my files on. Then when I put it in my Windows 7 machine, I got all the software needed from it, but then when I went to go delete files, it didn't free space, it was taking up more space! So I tried to format using Windows built in formatting software, but once again, it managed to take up more space rather than free it up. Any suggestions?

[BC_Programmer]

It is not physically possible to delete or remove content from a CD-R.

[DaveLembke]

Need to use a CD-RW Disc. Once a CD-R is burned the space can not be freed up. You can only add data to whatever free space is there. Surprised it allowed formatting of a CD-R. Usually only CD-RW discs take to formatting.

[Salmon Trout]

Since Vista, Microsoft has had the ability to put a "Live file system" on R and RW disks. It is packet-writing using the UDF file system. You can add files until the disk is full, and if, on an R or R disc, you "delete" files from the compilation thus created , they are no longer visible, but (of course) that won't free up any space, in fact it will use more space since an updated directory tree has to be written. The space is reclaimed on an RW disc however. The Live File System option is used by default by AutoPlay when formatting/erasing a CD/DVD -R or -RW.

https://en.wikipedia.org/wiki/Live_File_System

https://www.howtogeek.com/126547/htg-explains-live-file-system-vs.-mastered-disc-formats-in-windows/

[Geek-9pm]

You can not write to a CD-R disk once it has been used.
Is the above statement true?
For the original post, it is true.
But, hypothetically speaking, it can be done. At the present time the trick is not widely used or clearly documentation.  It is of historical value.**  Here is info from the archives of Computer Hope.

https://www.computerhope.com/issues/ch001586.htm
How to add more information to a CD-R disc
Windows XP and later provides a built-in capability of adding, or burning, files to a CD-R disc. In some cases (Windows 8 and earlier), this process asks whether you want to close the CD after burning the files to the CD-R disc. Closing the disc removes the ability to add more files at a later time, but makes it possible for nearly every drive and player to read the disc.
See the link above for more detail.

** A USB stick is now so economical and easy to use  that trying to use CD-R as backup media is of little value for most personal computer users.

[Salmon Trout]

You can not write to a CD-R disk once it has been used.

Define "used". You can write to a CD-R or CD+R disk in different ways. If you write a single session and close the disc, that's it. Finito. Nada mas. Rien ne va plus. Disc no longer writable. But you have been able to use 'multi session' writing since the 1990s, and also with packet writing you can add data until the disk is full.

[Salmon Trout]

I thought, "here's a use for that 25-stack of DVD+R discs I bought 5 years ago" (just before getting a smart TV and NAS, and also just before my DVD player died and was not replaced). I formatted a disk to UDF using AutoPlay and created 4 folders on it, into each one I then copied the same 24.5 MB of photos. Total data 98 MB. Then I did some steps...

1. Properties: 104 MB used. Some overheads apparent.

2. Ejected disk and put it back. Properties: 136 MB used.
You have to eject the disk before you can use it in another PC. This 'finalises the current session', or whatever the UDF terminology is, and, of course, adds data to the disk.

3. Deleted 1 folder. Was asked if I wanted to permanently delete. Yes.

4. Properties: 137 MB used.

5. Eject disk.

6. Put disk back in, Properties: 141 MB used.

This is all exactly like the OP described. The disk is still writable, I just added another 248 MB of pictures.

[Salmon Trout]

Ajfer03, if you want to reclaim disk space to re-use, you need to be using disks with RW at the end of the type name, like CD-RW, DVD-RW. But bear in mind the RW disks are more fragile than ordinary -R disks. More easily damaged by scratching, or getting hot, for example, and sometimes they just plain fail. You use it 3 or 4 times and then it's dead. Or won't read in another PC, or even the same PC. Why do you think flash drives are so popular?

[Salmon Trout]

https://en.wikipedia.org/wiki/Packet_writing

Packet writing allows users to create, modify, and delete files and directories on demand without the need to burn a whole disc. Packet writing technology achieves this by writing data in incremental blocks rather than in a single block.

Deleting files and directories of a CD-R using packet writing technology does not recover the space occupied by these objects but, rather, they are simply marked as being deleted (making them effectively hidden). Similarly, changes to files cause new instances to be created instead of replacing the original files. Because of this, the available space on a non-rewritable medium using packet writing technology will decrease every time its content is modified.

The most common file system for packet writing systems is UDF.

Due to the characteristics of optical rewritable media such as CD-RWs and DVD-RWs, the ability of data sectors to hold their contents diminishes when changing them frequently (since re-crystallized alloy de-crystallizes). To cope with this the packet writing system can remap bad sectors with good sectors as required. These bad sectors cannot be recovered by formatting the media.

[Geek-9pm]

Thanks for the link. I did not realize there was clear documentation about this trick.
Here is the key part of the trick:
Deleting files and directories of a CD-R using packet writing technology does not recover the space occupied by these objects but, rather, they are simply marked as being deleted (making them effectively hidden).
This concept existed before modern CD technology, but I do not know what it was called. It was used on an older form of optical storage.

[Salmon Trout]

It's not a "trick", The UDF disk format has been around since 1995, 23 years ago.

It is worth pointing out that data which has been "deleted" from a UDF-formatted -R (read only) optical disk is merely inaccessible. it has not gone away and can be accessed by data recovery tools.