Clean System Drive and Separate Storage Drive - How?

[Aguymac]

I want to understand some things about file deletion, "Trash"/"Recycle Bin"(windows), and "Erasing"/"Formatting".

1. Let's say I have a mac (or windows) with a main 'system' drive (with the OS on it), and a second (or more) internal drive just for 'file storage' (eg: media files, documents, etc.). And the reason for this is to keep the system drive "clean" and free of anything other than software, applications, etc.

Q1: If a file is deleted from the 'storage' drive, doesn't it end up in the "trash/recycle' bin? Does that deleted file now end up on the 'system drive'?
Q2: Is the answer different depending if the 'storage' drive is internal or external?
Q3: Will there be a trace of the deleted file on the 'system' drive in either of these scenarios?

2. If I use the computer's 'system' drive (the one I want to keep clean), to connect a second 'storage drive' that has a bunch of files, and then I "erase"/"format" the 'storage drive'...
Q4: What happens to the files then? Do they end up on the 'system drive' in any way? Or are they basically "written over" on the 'storage drive'?

I want to have a 'system drive' with only the OS and the software/applications that are needed, or that benefit from being on it on that drive. I want to have everything else (movies, music, documents, other stuff I probably won't keep forever) on a 'file storage' only drive. Is this possible.

I'm also wondering:
If I have a 'system drive' as I outlined, and a separate 'storage drive' (again, internal or external, please let me know if there's a difference), and I download a file (like some media file) to the storage drive, is there anything that ends up on the main 'system drive' - like a temp file or something.
It seems like it'd be very difficult - if not impossible - to not have unwanted files/info end up on the 'system drive'. Eg: Let's say I open the 'storage drive' to look at a folder/file, then I move something around and decide to delete an empty folder or something (a file), it's going to get "deleted" to onto the 'system drive', isn't it?

Maybe there's a proper way to do what I'm thinking of. Thanks for any help in helping me understand how.

 

[DeltaMac]

If you have items (files/folders) that you want to delete, drag those items to the trash. Those items are now in the trash, which is a folder on that drive. You will see that the trash icon shows that it has items in the trash.
If this is drive #2, and you eject the drive without emptying the trash, the trash icon will show empty (nothing in the trash). The trash exists only on the drive that is affected. Mount that same drive, and the trash icon will immediately show trash.
So, the trash affects only the drive with items in the trash. Other volumes or drives are not affected, except for the fact that the trash icon is always affected, by showing the presence of files/folders in the .trashes folder in any mounted volume or drive.
Another way to say this: deleting files on one volume does not affect any other volumes, neither internal nor external.
APFS format may have changed this slightly, as you can have multiple volumes in an APFS container that can all share the same space. Not sure if trash has any affect on more than one volume if the space is shared between multiple volumes. Might not be relevant, I've never checked for that kind of affect.
And, APFS volumes don't have to share space with other volumes -- has to be formatted that way.

 

[Mike Boreham]

The practice of having a small lean clean System Drive separated from the data made a lot of sense before Apple introduced the separate System Volume and -Data volume in recent macOSs. It probably still does in Windows.

Apple has taken the concept of the separate System and Data volumes a step further by making the System Volume completely unalterable. Users cannot add or take away one bit or byte from it. It is rigorously verified every boot and if it fails verification the machine won't boot. If it passes verification, a snapshot of it is made and the machine boots from the snapshot.

Absolutely everything we users add or do is in the -Data volume. The tiniest setting, temp files, prefs settings, user data and all apps we install are all in the -Data volume. This means there is no point in erasing and reinstalling to get rid of 'cruft'...there can be no cruft in the System Volume...it is all in the -Data volume. Your questions about keeping the System Volume clean are not relevant because we have no option to do otherwise. Incidentally it also means deleting the -Data volume returns the machine to factory condition and is what the new "Erase all content and Data" option does. No reinstalling necessary.

The Signed Sealed System Volume is integrated behind the scenes with the -Data volume to make it appear to users as a single drive.

The difference from what you may desire is that the System Volume and -Data Volume are on the same physical drive. If the drive fails you have to migrate a backup up your -Data drive to the new System Volume. You can't put the -Data volume on a separate drive from its System Volume, though of course you can put data on separate drives.

 

[Aguymac]

If you have items (files/folders) that you want to delete, drag those items to the trash. Those items are now in the trash, which is a folder on that drive. You will see that the trash icon shows that it has items in the trash.
If this is drive #2, and you eject the drive without emptying the trash, the trash icon will show empty (nothing in the trash). The trash exists only on the drive that is affected. Mount that same drive, and the trash icon will immediately show trash.
So, the trash affects only the drive with items in the trash. Other volumes or drives are not affected, except for the fact that the trash icon is always affected, by showing the presence of files/folders in the .trashes folder in any mounted volume or drive.
Another way to say this: deleting files on one volume does not affect any other volumes, neither internal nor external.
APFS format may have changed this slightly, as you can have multiple volumes in an APFS container that can all share the same space. Not sure if trash has any affect on more than one volume if the space is shared between multiple volumes. Might not be relevant, I've never checked for that kind of affect.
And, APFS volumes don't have to share space with other volumes -- has to be formatted that way.

Thanks for this explanation, I appreciate it.
So, essentially, files on a particular drive (second 'storage' drive), that are "deleted", stay on that drive - but are actually just set to a state where they're no longer visible to the user. And the "empty trash/recycling" function on the system drive just...marks them as space that can now be over-written? Is that correct? (I added that last part about being marked as able to be over-written because I recall reading something to that effect a couple years ago. Don't remember if it was specific to SSD's though.)

The difference from what you may desire is that the System Volume and -Data Volume are on the same physical drive.

Yea, I'm talking about multiple drives. So, while that's useful additional information about the volumes (and I do mostly understand and remember seeing the various volumes on the "main"/"system drive), I don't know that it really answers my question.
Even if apple has this new way of separating a single drive with macos on it into separate 'system' and 'data' volumes, if we only have one physical drive, then any data/files that are saved to that drive (regardless of what 'volume' they're on) are on that physical drive... Right? Eg: if someone who's skilled in "data recovery" got hold of the single physical drive, then they could potentially access or recover (deleted) files on it, regardless of the volumes being separate.
I want all those files (as I outlined; media, etc.) on a separate physical drive - probably external. So I can disconnect it if I want, and bring it to another computer.
Thank you very much for taking the time to help me. This is useful information, and I'll re-read both your posts again.

 

[chabig]

if someone who's skilled in "data recovery" got hold of the single physical drive, then they could potentially access or recover (deleted) files on it, regardless of the volumes being separate.

No. Everything on that drive (actually an SSD) inside your MacBook Pro is encrypted using a key securely stored in a separate section of the M1 chip called the Secure Enclave. If you have FileVault turned on (which you should), the decryption key is further linked to your login password. Nobody could recover any data off the SSD if it were ever separated from your specific logic board, nor could they decrypt any data without your login password. So if you are concerned about security, the best place for your data is on the internal SSD and you should have a very good login password.

 

[Aguymac]

No. Everything on that drive (actually an SSD) inside your MacBook Pro is encrypted using a key securely stored in a separate section of the M1 chip called the Secure Enclave. If you have FileVault turned on (which you should), the decryption key is further linked to your login password. Nobody could recover any data off the SSD if it were ever separated from your specific logic board, nor could they decrypt any data without your login password. So if you are concerned about security, the best place for your data is on the internal SSD and you should have a very good login password.

I hope I didn't post in the wrong sub-forum, but I don't have an M1 mbp. I have a late 2011 15" mbp, though I do have an 2.5" ssd as the/in the primary "bay" (I mean to say 'not in the optical bay as a secondary, that's where I have/had a second drive - hdd variety).
I also, don't have FileVault turned on, I never have. I remember reading (watching?) about it ages ago and some of the features, or potential things that could go wrong, scared me away from wanting to use it. I think it might have been something a little more detailed...maybe something about getting locked out/password related, or inaccessiblity to files written to a drive from that system with filevault turned on. Something..sorry, I can't remember.

Thanks.

 

[chabig]

I have a late 2011 15" mbp

Well then ignore everything I and others said about security as it pertains to your machine. You're running an old version of macOS on old hardware. DeltaMac's instruction about how the trash works still stands.

 

[Aguymac]

Well then ignore everything I and others said about security as it pertains to your machine. You're running an old version of macOS on old hardware. DeltaMac's instruction about how the trash works still stands.

Ok. Yea, I'm running catalina with dosdude1's patch tool.
I thought DeltaMacs' info sounded the closest.

Thanks, I appreciate your input.

 

[Mike Boreham]

I hope I didn't post in the wrong sub-forum, but I don't have an M1 mbp. I have a late 2011 15" mbp, though I do have an 2.5" ssd as the/in the primary "bay" (I mean to say 'not in the optical bay as a secondary, that's where I have/had a second drive - hdd variety).
I also, don't have FileVault turned on, I never have. I remember reading (watching?) about it ages ago and some of the features, or potential things that could go wrong, scared me away from wanting to use it. I think it might have been something a little more detailed...maybe something about getting locked out/password related, or inaccessiblity to files written to a drive from that system with filevault turned on. Something..sorry, I can't remember.

Thanks.

I am sure you will find bad things about FileVault (like any other topic you google) but I don't believe you have anything to fear about FileVault2, except perhaps some slow down on older hardware. Since security is your main concern I would say FileVault is worth a small penalty.