A couple iMac questions

[StephenCampbell]

I posted another thread about migrating from the 2013 to the 2015 iMac. I have now completed that successfully, and have a couple questions going forward.

First, I notice that when the 2015 machine starts up, the Apple logo/progress bar screen is present until the bar is only about half way, then the screen goes black, and then it flashes very briefly again right before the desktop comes in, and then it flashes a Third time as the desktop finishes settling in (desktop doesn't disappear, it's just like a brief flash cross-fade image of the Apple logo screen).

Is that okay/normal?

Secondly, I need to erase my 2013 machine before selling it, but the new Disk Utility has no zero-out option. There must be a way to erase the hard drive. Has anyone figured it out yet?

Thanks!

 

[CoastalOR]

Secondly, I need to erase my 2013 machine before selling it, but the new Disk Utility has no zero-out option. There must be a way to erase the hard drive. Has anyone figured it out yet?

I can't answer you're first question since I have no experience with the 2015 iMac.

The 2nd question; I have read that the current recommendation is to start the 2013 Mac, turn on FileVault, give it time to encrypt the drive, boot from the Recovery partition (command+r at boot up) and use Disk Utility to Erase the System drive partition. Using FileVault will prevent any access to any erased files since that partition was encrypted with FileVault.

 

[StephenCampbell]

I can't answer you're first question since I have no experience with the 2015 iMac.

The 2nd question; I have read that the current recommendation is to start the 2013 Mac, turn on FileVault, give it time to encrypt the drive, boot from the Recovery partition (command+r at boot up) and use Disk Utility to Erase the System drive partition. Using FileVault will prevent any access to any erased files since that partition was encrypted with FileVault.

Well I already did the "erase" in the new Disk Utility once, so the machine is "empty" now. Do I just install El Capitan from the recovery boot up and then do what you said?

 

[CoastalOR]

Well I already did the "erase" in the new Disk Utility once, so the machine is "empty" now. Do I just install El Capitan from the recovery boot up and then do what you said?

If the purpose is to make sure someone else does not find/access any old files then yes.

 

[StephenCampbell]

If the purpose is to make sure someone else does not find/access any old files then yes.

I've reinstalled 10.11 on the 2013 Mac now, but I just realized, if I do FileVault now, will that still affect all my old data that wasn't zeroed out? Because it's not "there" anymore, so FileVault probably won't encrypt it, right?

 

[DeltaMac]

The volume will be encrypted. The volume takes up all the space on your hard drive (and would include erased files, too.
When you then erase that encrypted volume, the erased files would be within that encrypted/erased region.
Your result will be erased files that are still encrypted - making it well nigh impossible to retrieve anything.
My take on that: It is at least equal to a "write zeroes to all blocks multiple times" erase, because of the pre-encryption.

 

[StephenCampbell]

The volume will be encrypted. The volume takes up all the space on your hard drive (and would include erased files, too.
When you then erase that encrypted volume, the erased files would be within that encrypted/erased region.
Your result will be erased files that are still encrypted - making it well nigh impossible to retrieve anything.
My take on that: It is at least equal to a "write zeroes to all blocks multiple times" erase, because of the pre-encryption.

Oh I see. So the encryption process should take the same amount of time whether I have 10GB or 2000GB of stuff on the drive? And the encryption process basically just scrambles the 0s and 1s?

 

[DeltaMac]

This is what happens: The data on the drive, whether available or erased, is encrypted by filevault. I won't (and you shouldn't) refer to the encryption as a basic process. Is it as simple as "scrambles the 0s and 1s"? I don't know . Some of those 1s and 0s will be part of previously erased data. So, any data is intermixed. All of it.
The point that you take from this is that the encryption is at least the equivalent affect of writing zeroes to erase the drive. Not the same, but equal in value. And - you should feel assured that your data, erased, or previously erased, is not considered recoverable by any means.