Partitioning a Mac hard drive


John Emmas

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I'm thinking about buying a Mac Mini or Mac Pro. Either way, I'll probably opt for a 1TB SSD. I'm assuming that (when it first turns up) the entire drive will be formatted as a single boot partition but eventually I'd like to partition the drive - maybe so I can dual boot with Windows and maybe with some extra space available to use as a dedicated data partition. So a couple of questions if I may...

1) When I last partitioned a drive it was for a Windows machine and IIRC there was a limit of only 4 x partitions (one of which could be an extended partition). I thinks this partitioning scheme was called MBR (Master Boot Record). Is MBR still used by modern computers or has it been replaced by something else now?

2) What's a good software package for partitioning and managing a Mac hard drive? Can Boot Camp do that for me or would I be better off buying something specialized?
 

Lufbrarunner

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If you want a windows partition, Boot Camp will do that for you.
You can partition your Mac drive with disk utility. The formatting will depend on the age of your Mac, Mojave will format the drives to APFS.
APFS volumes share storage space within a container, occupying a single partition. Adding and deleting APFS volumes is faster and simpler than editing a partition map.
 

John Emmas

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Thanks for the quick response, Lufbrarunner

What would be the deal with APFS and Windows? I'm guessing Windows won't recognize APFS volumes? (or from past experience, maybe it'll be able to read them but not write to them?)

Ideally I'd need a data partition which both OS's can read & write (last time I did this, FAT32 was the only type that was acceptable to both OS's)
 

honestone

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Regarding "Windows" formats, at least for Flash Drives, I can format them, via Disk Utility, either as MS-DOS (FAT), aka FAT32, or ExFAT. This might help:

"If you need to transfer files larger than 4 GBbetween Macs and PCs: Use exFAT. In all other cases: UseMS-DOS (FAT), aka FAT32."

I know that whenever I want to use a Flash Drive on our Samsung 65" Smart TV, the drive must be formatted as ExFAT. Yet, previously I wanted to give some movies to a friend, who had a LG TV, and for that one, only MS-DOS (FAT), ie, FAT32, worked.

And to make it more challenging, we recently purchased 2 Roku 4661R Streaming devices, and each one has a USB port. For that, here is what it says regarding the format of Flash Drives:

"USB drives may be formatted with different file systems. Roku Media Player supports drives that are formatted with the FAT16, FAT32, NTFS, EXT2, EXT3, and HFS+ file systems"

So, most likely, APFS would not be acceptable with that Roku player.

This should help you, especially in regards to Boot Camp:

https://support.apple.com/guide/disk-utility/format-a-disk-for-windows-computers-dskutl1010/mac

I assume that is applicable, even if you use Mojave.
 

John Emmas

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Thanks guys - I'm getting the impression that MBR and APFS are maybe incompatible - i.e. previously, I could have a drive configured as MBR and have 1 partition as HFS+ and another as FAT32 and another as NTFS or whatever. But what's the deal with APFS? If I have an MBR configuration, can one of the partitions be APFS (or would it be better to have them on different drives - one APFS and the other MBR)?
 

Lufbrarunner

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You can still create partitions on an APFS drive, in fact Boot Camp will do this for you, The partition will be outside of the APFS container, inside the APFS container you can create separate volumes. you could also create another partition for Data outside of the APFS container and format it to suit windows. This can all be done with Disk Utility.
 

John Emmas

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Thanks Lufbrarunner, What worried me is that Windows (AFAIK) expects the disk scheme to be MBR. So would the disk scheme still be MBR but with one of the partitions formatted for APFS?

This would be similar to older Macs - where the disk scheme was MBR but with the Mac partition formatted as HFS+.
 

honestone

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Even though I don't need a Windows partition on any of my SSDs, this is still a somewhat confusing scenario. I have 3 external Samsung SSDs: two of them are 512 gig 850 Pro models, and one is a 500 gig 860 EVO model. Given that I am using Mojave, the initial Erase and Format for each of those SSDs, via the Mojave version of Disk Utility, formats them as APFS (that is the simplest APFS "version" that I chose):

https://support.apple.com/guide/disk-utility/file-system-formats-available-in-disk-utility-dsku19ed921c/18.0/mac/10.14

For the 2 840 Pros, I have 3 partitions. Two of those partitions are used for my SuperDuper! backups for each of my Macs, and the third partition contains various "data" files: Photos, Movies, TV Series, etc. For the 860 EVO, it currently contains tow partitions, and they are the final High Sierra SuperDuper! backups (needed to have them, as Tech Tool Pro does not yet have a "full" Mojave version available). Eventually I will want to use the EVO SSD for other purposes.

Now, there is this:

https://support.apple.com/guide/disk-utility/partition-a-physical-disk-dskutl14027/18.0/mac/10.14

Note that it says "If you’re partitioning your internal physical disk because you want to install Windows, use Boot Camp Assistant.".

What those links do not cover is if you want to have a "Windows" data partition. That seem so be what you want.
 

Lufbrarunner

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Although you can create an exfat partition on the internal drive it will not be visible to the boot camped windows OS.
Using an external drive works well, I did this when I needed to boot to a windows partition to run photoshop. All my photos were on an exfat formatted drive and could be accessed by both OS's.
 

honestone

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If you plan on purchasing an external drive, the Samsung 860 EVO 500 gig SSD is an excellent choice. I recently purchased one, and it is a pleasure to use. It has had numerous excellent reviews. Also, here in the US, it has recently been on sale at Amazon for as low as $68, definitely a super price.
 

John Emmas

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If you want a windows partition, Boot Camp will do that for you.
You can partition your Mac drive with disk utility. The formatting will depend on the age of your Mac
Suppose I just want to reduce the size of my Mojave partition (i.e. to create some free space which I can later use as FAT32 volumes or whatever). Is that possible and what would be best for achieving it (Boot Camp or Disk Utility) ?
 

John Emmas

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Oops, I've already started it this morning!

I partitioned my drive to use 250GB for Mojave with 750GB spare. I intended to use maybe 100GB of that for Windows 10 - BUT - when I run Boot Camp it gives the impression that it'll create a 100GB partition for Windows and then use the other 650GB for MacOS (even though Mojave is already installed on its own partition).

What will happen on that 650GB space? Will Boot Camp leave it as it is (i.e. empty)? Or will it relocate Mojave there for some reason?
 

Lufbrarunner

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I would have run boot camp first to make the windows partition and then resized the MacOS partition.
Did you create the 750gb partition inside or outside of the APFS container?
 

John Emmas

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Eventually I created it outside (assuming that the Windows partition would need to be FAT32 or whatever) - but I did initially try the boot camp utility. However, that gave me a message saying to set my partition sizes first because partitions can't be re-sized after running boot camp (seems unlikely to me - but that's what it said...)
 

Lufbrarunner

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I think the windows partition size would be 'fixed' but the MacOS partiton should still be resizable.
 

John Emmas

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Things are going from bad to worse...

Boot Camp insists on having a Windows ISO image (which would normally be on a CD/DVD etc). But of course, the Mac Pro doesn't have a DVD drive so I downloaded an ISO image from Microsoft and put it on a USB stick. But now Boot Camp is telling me it can't run because there's a USB stick attached!!! :(

Suppose I copy the ISO image onto OS-X's main drive somewhere. Will that work or will that go unrecognised?
 

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