[dmetzcher]

Last night, I ran an "Erase Free Space" operation on my Mac Pro. The drive is 500GB, so I ran it because I was mainly curious to see how long it would take to complete. I selected "Zero Out Data" as the security option, so that it wouldn't take forever, and let it run.

After about two hours, I needed to go to bed. The process had not finished, but was at the point where it was "creating temp file". I clicked the skip button, but nothing stopped. I waited another 30 minutes or so, clicking "Skip" several times during this period. Every time I would click Skip, the button text would change to "Skipping", but nothing would happen. After switching to the Finder, the button text would go back to "Skip", and I could click it again.

After about 30 minutes of this, I noticed that my available drive space on the startup disk (on which I was wiping the free space), was down to about 10MB. I watched as it got down to 0MB, and got a warning from the OS stating that my startup disk was almost full, along the way.

I quit Disk Utility, after first being warned that quitting some operations could result in an unusable disk. I rebooted...twice. Each time, the drive space would be at less than 100MB available, and would diminish to 0MB again. Then, I noticed that there was something in the trash. One file was a sparse disk image. It was about 300GB. The other was smaller, and was not a disk image. Both were in a folder in the trash called "Recovered Files".

I deleted both files, and got my free space back.

Here are my questions:
1. Are there going to be any bad results from all this, or is this normal?

2. By quitting Disk Utility while it was wiping free space, did I cause any problems that I didn't correct by deleting the recovered files? Is it normal for all free space to disappear while the wipe option is running?

3. Do I need to run the wipe free space again, if I really want free space wiped, or did it more or less complete, leaving those files only because I quit the process near the end? (In other words, would Disk Utility have deleted them if I had left it to finish on its own.)

4. It occurred to me, during the wipe process, that wiping free space touches an awful lot of the drive. If this is done often, wear and tear on the drive, I assume, it much higher. How often is too often? (And I understand that this would be a best guess, at best.)

Thanks for reading this whole thing!

[- - e r i k - -]

Why would you need to wipe the free space? Have some bad files you don't want the feds to see?

[TETENAL]

You don't need to erase free space often. Just use "Secure Empty Trash" to delete your sensitive financial data or whatever. "Erase free space" basically creates a temporary file the size of the free space of the disk and securely deletes that. So obviously the free space temporarily goes down to none while Disk Utility does that.

[dmetzcher]

Originally Posted by - - e r i k - - 

Why would you need to wipe the free space? Have some bad files you don't want the feds to see?

Not yet.
No, I really just wanted to see how long it would take on the Mac Pro, given my configuration. I know it takes forever on my iBook, and I wanted to see if it would be that much faster. It is, but, being that the drive is 8-10x the size of the iBook drive (in terms of free space), the difference in speed isn't anything to write home about, because it's doing more work.

[dmetzcher]

Originally Posted by TETENAL 

You don't need to erase free space often. Just use "Secure Empty Trash" to delete your sensitive financial data or whatever. "Erase free space" basically creates a temporary file the size of the free space of the disk and securely deletes that. So obviously the free space temporarily goes down to none while Disk Utility does that.

Good point about secure empty trash. I do that from time to time with sensitive files (which are few). I also have a keyboard shortcut defined on the iBook for it, so I'll create one on the Mac Pro.

So...I'm ok then in terms of that large file? Basically, I didn't really secure-wipe anything, if what you say is true, because I simply emptied the trash, rather than secure-emptying the files that were in it. Oh well, doesn't really much matter, I guess, since it was just a test. Things are also running really well anyway, so nothing terrible has happened.

Thanks!

[- - e r i k - -]

Well, technically if the file was created and you deleted it, you actually did wipe (most of) your free space. Not securely, sure, but you did create an extra layer

[dmetzcher]

Originally Posted by - - e r i k - - 

Well, technically if the file was created and you deleted it, you actually did wipe (most of) your free space. Not securely, sure, but you did create an extra layer

Ah. Right, because the file would have been created over top of all the free space containing deleted files. I'm just glad it's gone. The thought of rebuilding this thing, now that it's running, gives me nightmares. I hadn't actually run a backup yet, at the time, so I would have had to start over.