How to get access to hidden folders from another Macintosh HD (Users/Applications)

backupbootfinderhard drivepermission

I need to back up the main Users folder, as well as all other data, from my main Mac (2013 13" MBP). I've gotten the dreaded UEFI-inspired flashing question mark, and tried running Disk Utility's repair options on it, both on in recovery mode on the main machine, as well as from another machine (with the drive connected via a SATA-to-USB cable into another older MBP — my wife's).

B/c I didn't have the option of backing up the machine "normally" — copying all files and folders through the Finder of my wife's machine, due to perms issues — I've used the utility app Disk Drill to create a .dmg file, encompassing the whole drive's contents (a byte-for-byte copy, is what it's called in this software).

First, is there any other way of getting to the main Users folder, and the Applications, too? They're all hidden, as they were installed/created by a user not present on my wife's machine? (I just wanted the assurance of copying the files by hand, too, before wiping my machine's 1TB SSD and restoring the files from the disk image file I'd created in Disk Drill.) Secondarily (as a bonus question), is there anything suspect with the above approach?

Many, many thanks, to all who take the time to read, much less answer.

Best Answer

Since your failed system was on Catalina, which uses the Read-Only System Volume scheme with separate System and Data volumes, it sounds like you backed up only the System volume. The /Users directory, however, is stored in Data.

One possibility for why you did this is that the Data volume might be corrupted and unmountable and therefore didn’t show up in Disk Drill, so the System volume was your only obvious choice.

Another possibility is that High Sierra is two major OS releases behind Catalina. In general, it is inadvisable to mount an APFS volume from one OS using an older OS because APFS is a moving target and there are changes and additions to the format & filesystem driver that occur between releases. While unlikely, your wife’s machine may not be able to recognize the /Data volume. (It’s also unlikely but possible that mounting it on the old OS could have unintentionally caused damage to the newer format.) I haven’t used Disk Drill so it is possible that it did image your entire drive and the Data volume is still hiding in the .dmg, waiting to be read on a newer OS.

As a general rule, any time disk corruption is suspected, your #1 goal is to minimize disk usage (especially when hosted on the faulty machine) until you’re ready to perform a repair or transfer. Repair is no longer an option since Disk Utility couldn’t do it and no other APFS tools are currently available. So you’re left with transfer.

To maximize your chance of transfer, you need to be running at least the same version of OS on the lifeboat unit. You would also ideally be able to remove the physical drive from the target machine and place it in an external enclosure. Even so, your chance of success is slim if the Data drive failed to appear. You do need to be able to accept the fact that your data may be gone. (You could take out the SSD and set it aside, waiting for DiskWarrior 6 to come out and give you another chance at recovery.)

In short, try again with a Catalina machine, but minimize how much time the drive is powered on and be ready to call it a day.

Related Solutions

Shared Directory Permissions on MacOS – How to Manage File Access

You can't do this with traditional POSIX-style permissions, but you can with inheritable access control entries. To allow read+write access for the entire "staff" group to everything in /Users/Shared/reallyshared, you'd use:

sudo chmod -R +a "staff allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit" /Users/Shared/reallyshared

The file_inherit,directory_inherit part means that this access control entry will automatically be added to new files & folders created inside this folder, but it doesn't automatically apply to items already there (that's why I added the -R flag to chmod -- that applies it to everything currently within the folder), and it won't be applied to items created somewhere else and then moved into this folder (I don't know of a way around this, sorry).

MacOS – Unmountable HDD – Can I save the data

I figured it out and I'm leaving my solution here in case someone else has the same issue:

I bought Disk Drill ($90 for the Pro version). Had it go through all recovery options for the drive (took 6 hours for a 3TB drive), which resulted in a list of files, organized by file type and without file info.

For example, all of my JPGs were in one folder, with names like file00001.jpg, file00002.jpg, etc.

I saved the session, went back, and had it search for lost HFS partitions and all my folders and file names are back.

UPDATE I started transferring my files over to a new drive, and unfortunately none of them are readable. All of them throw an error that says the file is either empty, or damaged/corrupted. Taking a couple steps back and transferring over the deep scan files instead - the unnamed/sorted-by-file-type versions. Although those don't have any organizational data, they are not damaged.

Any ideas of how I can recover my files WITH information intact would be much appreciated... Or a way to salvage the map of the original drive.

Best Answer

Related Solutions

Shared Directory Permissions on MacOS – How to Manage File Access

MacOS – Unmountable HDD – Can I save the data

Related Question