I noticed that my hard drive is divided into two partitions. They are Macintosh HD and Macintosh HD – Data. I also noticed that while the Macintosh HD Partition is mounted the Macintosh HD – Data portion is not mounted. Is this normal? I’m viewing this in disk utilities in recovery mode.
I was working with apples tech-support on an issue I had and was in recovery mode when I noticed that my Macintosh HD – Data partion was not mounted. While the Mac Hd was. Is this normal?
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George Motherway
Starting with Catalina, this is how it works. The System is on a special read-only partition. The rest of your files are on the "Data" partition. This is a great security measure. The way it is designed, you see both as one "Macintosh HD" as normal with your System in the right place, just not modifiable.
https://support.apple.com/en-us/HT210650
But why is the HD - Data portion listed as “not mounted” while the system portion is mounted?
George: That's just the way it is represented in Disk Utility. It isn't "mounted" as a separate drive. This isn't something you need to manage or take an action here -- it is working as it should.
Time Machine won't do a backup with Macintosh HD and Macintosh HD - Data. Why did Apple do this and how can I get around it?
Luke: What do you mean, exactly? Is there an error message? Those two partitions are irrelevant when it comes to backups. Time Machine will just back up your files. The way the drive is formatted doesn't affect that.
Tried again to run Time Machine to 'My Book' external drive, got following messages:Time Machine couldn’t complete the backup to “My Book”, Two of the disks to back up have the same name. Rename one of the disks named “Macintosh HD - Data”. Backups to this type device used to work.
Luke: So it sounds like you have two volumes on your drive named "Macintosh HD – Data." By chance did you ever wipe and reinstall macOS on that Mac? If so, it sounds like you didn't wipe the drive properly when you did that.