Why is the specified file locked?

Question

Hi
I used a CD-RW & copied a file. When I insert the CD in the slot the sequence opens. When I close & save I get "File Error: The specified file is locked."
What is wrong? Thank you, Faruk

Answer 1

By "within application" I mean do you open the file from the disc, change it, then click save in whatever application the file opens in? That won't work.
I think the confusion is about how CDs/DVDs work as storage media. They are not like old floppy disks, your hard disk, or a USB thumb drive. You can "save" to your hard disk or a thumb drive - but you "BURN" a CD/DVD. When you burn a CD-ROM/DVD-ROM you are making a permanent disc. You cannot 'resave' files to the disc, you cannot add more files to a disc that has been burned - it's locked in that configuration. CD-RW and DVD-RW discs are a little different - with those you still burn and make a locked disc, but with those discs you can erase them and re-burn them (and you MUST completely erase them and re-burn them, you can't just add a file). You still cannot modify files on the discs. Think about it - the ROM in CD-ROM stands for Read Only Memory, meaning you can read from the disc but not write to it (once it's burned).
Your out of disc space error could be one of two things. Either the file is too big for a DVD (single layer holds ~4.7 GB) or you've already burned something to that DVD.
You've noticed that a blank CD-ROM has a capacity of ~700 MB, right? If you insert that blank disc, copy a 2 MB file onto it, then click burn you probably expect there to be 698 MB of free space...NO. If you Get Info on that disc, you will see Space Used = 2 MB, Free Space = 0 MB. That's what I mean by locked - it's burned and you're done! NO more adding files. So when you try to save a file to the disc you've already burned, you cannot. With your hard drive, when you change a file what you're really doing is deleting the last version and writing a brand new version of the file to the hard disk. But like I said, you can only write a file to a CD/DVD when you burn it. So you can't save the modified file.
The idea with CD/DVD discs is that you burn the final versions of your files to them to archive them, send them to friends, etc. If you're working on a file, you do that on your hard disk.