Secure Erase Free Space Error Message

[pigoo3]

Very helpful thread. Is there any way of knowing whether the "erase" (i'm aware it is actually a write-over) has worked?
Thanks

Like pm-r mentioned. Probably the best way to check things is to use a data recovery app to see if it "sees" the data you securely erased. If the data recovery app doesn't "see" it…then recovery should be very difficult by the average user. The down-side to this is…most good data recovery apps aren't inexpensive (usually cost $99-$120). The up-side is…some data recovery apps have free trials or free demo's…which usually allow for scanning (but not recovery) of files (which sounds like you only want to do a scan anyway).

- Nick

 

[chas_m]

It should also be noted that BROADLY speaking, secure erase is nearly always unnecessary and very time-consuming compared to the normal procedure. Obviously, one might wish to zero-out the hard drive if one is giving their machine/selling their machine away, but in typical day-to-day use for non-criminals or non-secret agents, secure erase is overkill.

 

[Stuv]

Thanks Guys, I'll consider the suggestions, although I'm wondering if PM-R's reply "Your easiest way is to waste your time...." is suggesting that the Mac programme is so reliable, when it doesn't show an error message, that there is really no need to go any further?

 

[Stuv]

And on another note, having just installed El Capitan on my iMac (works much quicker on my machine than Yosemite) I now find that there is no ' secure erase free space' option available. I looked for it via the Restart procedure, above, but it isn't there either.
Another forum is saying that Apple dropped it because it wasn't that secure anyway and there is now secure empty trash instead, with the whole file 'erased' not just the address. So why is this erase any better than the previous, but now apparently unavailable 'erase free space'? And also that doesn't seem to solve the problem of how to securely 'erase free space' of the deleted files already there. Any suggestions please?

 

[galilao]

Erasing free space

And on another note, having just installed El Capitan on my iMac (works much quicker on my machine than Yosemite) I now find that there is no ' secure erase free space' option available. I looked for it via the Restart procedure, above, but it isn't there either.
Another forum is saying that Apple dropped it because it wasn't that secure anyway and there is now secure empty trash instead, with the whole file 'erased' not just the address. So why is this erase any better than the previous, but now apparently unavailable 'erase free space'? And also that doesn't seem to solve the problem of how to securely 'erase free space' of the deleted files already there. Any suggestions please?

Hello: Got this from MacWorld OS X Hints. I tried the following Unix command and it seems to work. Be sure to back up your drive first.

sudo diskutil secureErase freespace [z] /dev/disk[disk or partition number]

If z = 1 - Single pass randomly erase the disk
If z = 2 - US DoD 7 pass secure erase
If z = 3 - Gutmann algorithm 35 pass secure erase

You can get the disk or partition number from About This Mac.

I ran in El Capitan's Terminal app the following Unix command inside the quotation marks: "sudo diskutil secureErase freespace 1 /dev/disk0s3". Press the return key and the system will ask for your password. Enter your password, press return and your Mac should start securely erasing.

My partition number is 0s3 but yours will be different. Again, remember to back up your drive first because if the sudo command is misused, you might have to reinstall everything. Hope this helps.

 

[pm-r]

Hello: Got this from MacWorld OS X Hints. I tried the following Unix command and it seems to work. Be sure to back up your drive first.

Unless of course the user is using a SSD drive in which case they should do some reading, like Apple's article:
"Note: With an SSD drive, Secure Erase and Erasing Free Space are not available in Disk Utility. These options are not needed for an SSD drive because a standard erase makes it difficult to recover data from an SSD. …"
https://support.apple.com/en-us/HT201949

I have no idea if Terminal can tell the difference between a HDD and any SSD when running such a command, but I'm sure not going to be a tester and try…




- Patrick
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[MacInWin]

You also don't want to erase, secure or otherwise, SSD free space because that consumes write cycles on the SSD, shortening the life of the drive.

 

[galilao]

Hello Patrick,

So far as I know, Terminal cannot tell the difference between a HDD and a SSD. I only securely erase the free space on a HDD.

Cordially,

Scot "Bruce" Nakamura

 

[galilao]

Hello Jake,

Yes, you are correct. I prefer HDD's for that reason.

Cordially,

Scot "Bruce" Nakamura