Advice Article TS1974 to create HD space to turn off FileVault doesn't work

Question

I would like to turn off FileVault (prior to fitting larger internal HD in my G4 PwrBk).
I have carefully followed instructions in the above article which falters at step 19, because the new Sparse Disk Image of my Home folder, created on an external HD, is 23GB in size and there is only 9Gb left on my resident laptop HD. This is precisely the problem the above procedure is supposed to get around!
So I can't copy the newly created sparse disk image back to my new user-account which is supposed to replace my FV protected original user account! I must be doing something stupid as the whole point of Apple's guide is to get around insufficient space on the HD in the first place!
As an aside I've discovered a couple of errors/omissions in the above article. I'd be pleased to list them for our moderator if considered helpful for others.
Please can anyone help me understand:
1. How is above process supposed to save space and
2. How can I copy my new Home Directory back to a nearly full HD without first deleting the original account?
Apple's article seems weak on this aspect.
Many thanks to all techies who can help.

Answer 1

I'm not sure about the instructions in [Apple support article TS1974|http://support.apple.com/kb/TS1974?viewlocale=en_US] , but here are some thoughts.
That support article includes
When turning FireVault on or off in Security preferences in Mac OS X 10.4 or later, this alert may appear:
"There isn't enough space on your hard disk to turn on (or off) FileVault"
The amount of free space stated as needed may be much greater than what is available ("4000 GB of free space is needed" may appear, for example).
There can't really be "4000 GB" of free space needed, and so if you see that message it may instead indicate some system error. If that is the case then there might actually BE enough free space on the HD, and it may be that situation that the support article is trying to remedy. The method given, which doesn't delete the old FV data before importing the new data, doesn't otherwise make sense, as you say.
In your case, where there really isn't enough free space, I also would instead try cloning to a bigger drive. The idea would be to clone your entire internal HD to a larger external volume, boot from it, turn off FileVault from there, and then test everything thoroughly. If all functions well on the external volume with Filevault off, then you would clone it back to the internal HD. This has the advantage of not deleting anything on your internal HD until you are sure that the clone works properly.
One important caveat - you can use software such as Carbon Copy Cloner to clone to the external drive initially, but *do not make the clone while logged into the FileVault account*. Instead create a second (non-Filevault) admin account, and run CCC from there. From CCC help:
Working with FileVault home directories
FileVault protects the contents of your home directory by enclosing it in an encrypted disk image. When you log in, the encrypted disk image is unlocked via your login and password and mounted for use as your home directory. Mounted disk images pose an interesting problem to incremental backup utilities. By simply being mounted and accessed (e.g. via browsing the contents), the content of a disk image, and thus the disk image file itself, is modified. If you run CCC while logged in to a FileVault-protected account, there is a strong chance that the FileVault disk image will be modified while it is being backed up, resulting in a corrupted version of the disk image on your backup volume. Also, because the contents of your FileVault-protected home directory are technically on another volume, CCC will not back up the contents of your home directory when backing up your root filesystem (e.g. your boot drive).
For these reasons, you should either exclude your FileVault disk image file from your backup routine while logged into a FileVault-protected account (and set up a separate routine for backing up the contents of your home directory), or you should only run CCC while logged into an account that is not protected by FileVault.
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