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APFS - "Data" Partition

redAPPLE

macrumors 68030
Original poster
May 7, 2002
2,621
2
2 Much Infinite Loops
hello.

i just noticed something.

checking my storage drive in disk utility, it shows that i have 2? partitions. one is macintosh hd and the other is macintosh hd - data.

the drive is configured as an APFS drive. is this normal, that a "data" partition is automatically created?
 

casperes1996

macrumors 603
Jan 26, 2014
5,595
3,423
Horsens, Denmark
Yes, and you're using it actually. The OS generally makes this transparent, outside of disk utility and similar tools, but the main Macintosh HD volume is actually read-only and just for the OS and core stuff. Everything you add to your computer happens on the Data partition. It's a security mechanism
 
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redAPPLE

macrumors 68030
Original poster
May 7, 2002
2,621
2
2 Much Infinite Loops
Yes, and you're using it actually. The OS generally makes this transparent, outside of disk utility and similar tools, but the main Macintosh HD volume is actually read-only and just for the OS and core stuff. Everything you add to your computer happens on the Data partition. It's a security mechanism

thanks for the reply.

so should want to sell the mac in the future, do i need to erase „both“ partitions?

maybe you have a link where this is explained?
 
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casperes1996

macrumors 603
Jan 26, 2014
5,595
3,423
Horsens, Denmark
thanks for the reply.

so should want to sell the mac in the future, do i need to erase „both“ partitions?

maybe you have a link where this is explained?

You need to erase the higher level device - In Disk Utility, go to the View menu and pick "Show All Devices" - Show Only Volumes is default. Then you can pick the hard drive/SSD and erase that instead of either of the volumes.


There's a little from Apple's own page about it, though it's not really super detailed about the reasons for why it's done, and it makes it seem a bit scarier than it actually is - Most locations are still writeable because they will be mapped to the data volume transparently
 
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