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User profile for user: sorealist
sorealist Author
User level: Level 1
8 points

Hard disk partition missing in dual boot Macbook Pro

I recently partitioned by HD to allow for a dual boot system (one with Catalina and one with Yosemite) for compatibility reasons.


On the Catalina Boot, I can see both my HD partitions but on the Yosemite boot, it only shows the HD partition that it is installed on.


I need the Yosemite boot to access files from both partitions. It seems like this may be a permissions thing but I can't seem to find any resources online so hoping the community can!?


I should add that initially, I had two Yosemite boots running and had no problem seeing both partitions. I then upgraded to Catalina on one, and lost the ability to see both partitions on the remaining Yosemite boot drive.

MacBook Pro 15″, macOS 10.15

Posted on Jul 25, 2021 8:09 AM

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User profile for user: HWTech
HWTech
User level: Level 9
60,758 points

Posted on Jul 25, 2021 6:14 PM

Catalina uses the APFS file system which Yosemite knows nothing about which is why Yosemite cannot see any files from Catalina or even select Catalina as a Startup Disk from within Yosemite. Any files you want to share between Catalina and Yosemite need to be located on an HFS+ volume or on a shared network drive (NAS).


I never recommend multiple partitions on any drive, but especially not on a boot drive since users almost always select the wrong sizes for the partitions when they run out of storage space. When they try to "fix" it, then usually end up losing access to their files (sometimes permanently) and many times break macOS so it won't boot to either OS. If you need to boot another OS, it is much better and safer to install the older OS on an external drive.


Make sure to always have frequent and regular backups.


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User profile for user: HWTech
HWTech
User level: Level 9
60,758 points

Jul 25, 2021 6:14 PM in response to sorealist

Catalina uses the APFS file system which Yosemite knows nothing about which is why Yosemite cannot see any files from Catalina or even select Catalina as a Startup Disk from within Yosemite. Any files you want to share between Catalina and Yosemite need to be located on an HFS+ volume or on a shared network drive (NAS).


I never recommend multiple partitions on any drive, but especially not on a boot drive since users almost always select the wrong sizes for the partitions when they run out of storage space. When they try to "fix" it, then usually end up losing access to their files (sometimes permanently) and many times break macOS so it won't boot to either OS. If you need to boot another OS, it is much better and safer to install the older OS on an external drive.


Make sure to always have frequent and regular backups.


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User profile for user: sorealist
sorealist Author
User level: Level 1
8 points

Jul 26, 2021 3:18 AM in response to HWTech

Thanks @HWTech, that makes sense now.


I did see that there was some software called Paragon Retrofit on the market that allowed older OSX's to see APFS drives but it seems to be discontinued.


Either way, this would be a workaround and I will heed your advice and concerns regarding partitioning and replace my optical drive with a second SSD.


From terrible past experiences, I have timemachine'd this at every step just in case so if all goes wrong!


Thanks for your insight. Much appreciated!

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Hard disk partition missing in dual boot Macbook Pro

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