Slate urges against early odoption of new MacOS.

[Sardi]

Originally Posted by JFreak

Two partitions should not interact with each other -- when you update one, another should be left intact

But it’s a firmware update for the hardware in his Mac, so regardless of the individual drives and partitions, it will globally affect his system.

However, I have never heard of a FW update preventing backwards compatibility and booting of an older OS. I have High Sierra on one of my laptops and recently cloned back an old Mountain Lion partition to the same drive without any issue. I’ve done the same sort of thing countless times in the past on MacBooks, iMacs and Mac Minis - never an issue.

However, if this is relating to an older MacPro with a patched system allowing it to run newer versions of Mac OS, then I don’t know. Technically, you’re using an unsupported configuration and thus if a newer EFI update did something to your system, it’s not really on Apple to fix it. IOW - it’s up to the user and the help of the internet to get that machine up and running again.

I sense that’s probably the hesitation.


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[musicman691]

Originally Posted by Sardi

But it’s a firmware update for the hardware in his Mac, so regardless of the individual drives and partitions, it will globally affect his system.

However, I have never heard of a FW update preventing backwards compatibility and booting of an older OS. I have High Sierra on one of my laptops and recently cloned back an old Mountain Lion partition to the same drive without any issue. I’ve done the same sort of thing countless times in the past on MacBooks, iMacs and Mac Minis - never an issue.

However, if this is relating to an older MacPro with a patched system allowing it to run newer versions of Mac OS, then I don’t know. Technically, you’re using an unsupported configuration and thus if a newer EFI update did something to your system, it’s not really on Apple to fix it. IOW - it’s up to the user and the help of the internet to get that machine up and running again.

I sense that’s probably the hesitation.


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Mine is a 5,1 2012 cheesegrater. So it's not a patched system.
Where I get conflicting info is in regards to ssd's. As we all know HS changes an ssd to APFS which is all well and okay. What I can't find concrete info on is with a dual boot system as my system ssd is split into OSX 10.10.5 and OSX 10.12.6. Most web pages I've found only deal with a single partition.

Before you cloned back the ML partition how was your system drive formatted - APFS or HFS? I'm under the impression that anything older than Sierra won't run on APFS. I've only ever cloned back and forth within HFS. I run Carbon Copy Cloner.

I know this is taking the thread a little OT but I want to get my ducks in a row before PT 2020 hits. If it ever does

[JFreak]

I would have to test this when I have enough time, but I'm thinking if you have partitioned your drive to two HFS+ partitions and then install there, that drive cannot convert to APFS

[Sardi]

Originally Posted by musicman691

Mine is a 5,1 2012 cheesegrater. So it's not a patched system.
Where I get conflicting info is in regards to ssd's. As we all know HS changes an ssd to APFS which is all well and okay. What I can't find concrete info on is with a dual boot system as my system ssd is split into OSX 10.10.5 and OSX 10.12.6. Most web pages I've found only deal with a single partition.

Before you cloned back the ML partition how was your system drive formatted - APFS or HFS? I'm under the impression that anything older than Sierra won't run on APFS. I've only ever cloned back and forth within HFS. I run Carbon Copy Cloner.

I know this is taking the thread a little OT but I want to get my ducks in a row before PT 2020 hits. If it ever does

If that’s your hesitation, then I can put your mind at rest. Upgrading a partition to APFS will do absolutely nothing to your other HFS partition. My studio computer has an SSD with two partitions - one with Sierra and one with High Sierra. No issues. I’ve also wiped that HS partition and installed Sierra on it. Again, no issues.

It’s the same as buying a new drive and having to format it from its existing FAT or NTFS to HFS etc. You can erase partitions and have different formats. There is no issue. This is exactly how Bootcamp works on a Mac. One drive, two partitions, two different file systems.


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[musicman691]

Originally Posted by JFreak

I would have to test this when I have enough time, but I'm thinking if you have partitioned your drive to two HFS+ partitions and then install there, that drive cannot convert to APFS

Originally Posted by Sardi

If that’s your hesitation, then I can put your mind at rest. Upgrading a partition to APFS will do absolutely nothing to your other HFS partition. My studio computer has an SSD with two partitions - one with Sierra and one with High Sierra. No issues. I’ve also wiped that HS partition and installed Sierra on it. Again, no issues.

It’s the same as buying a new drive and having to format it from its existing FAT or NTFS to HFS etc. You can erase partitions and have different formats. There is no issue. This is exactly how Bootcamp works on a Mac. One drive, two partitions, two different file systems.


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Thanks much to the two of you - you've put my mind to rest. As I said I researched this and just couldn't find definitive answers one way or the other. Gives me something to do this weekend. I've got time between projects so it should be a good time to forge ahead.