Guide: Multibooting UEFI on Separate Drives

[Going Bald]

Incredibly clear and helpful. Two follow ups:
-from OSX will the win drive be viewable natively on finder, just as another drive?
-Any reason for why >1tb? I have old drives around to use

Yes - viewable as any drive in finder.
Size limitation of FAT32 formatting

 

[Nikinp]

Thanks.
I did a bit of reading and I wanted to double check you meant bigger than 1Tb or smaller than 1Tb? I read in some places there are limitations if the size is 2tb or more, but nothing in relation to drives that are smaller than 1tb. Also if you meant bigger than 1tb - will any drive sold as 1tb be ok? (since droves often say 1tb and very often are slightly less - and I don’t know if that is an issue) And I don’t want to have to invest in the next SSD up which is 2tb and more than double the price.
Many thanks

 

[Going Bald]

Thanks.
I did a bit of reading and I wanted to double check you meant bigger than 1Tb or smaller than 1Tb? I read in some places there are limitations if the size is 2tb or more, but nothing in relation to drives that are smaller than 1tb. Also if you meant bigger than 1tb - will any drive sold as 1tb be ok? (since droves often say 1tb and very often are slightly less - and I don’t know if that is an issue) And I don’t want to have to invest in the next SSD up which is 2tb and more than double the price.
Many thanks

Sorry, that was a typo - should have been 2 TB. When formatting a drive larger than 2TB with FAT32 you must break in into partitions smaller than 2TB due to the size limit of the format.

For the FAT32 typical value of 512 bytes per sector:
FAT32 maximum : 8 sectors per cluster × 268,435,444 clusters = 1,099,511,578,624 bytes (≈1,024 GB)
FAT32 maximum : 16 sectors per cluster × 268,173,557 clusters = 2,196,877,778,944 bytes (≈2,046 GB)
[FAT32 maximum : 32 sectors per cluster × 134,152,181 clusters = 2,197,949,333,504 bytes (≈2,047 GB)]
[FAT32 maximum : 64 sectors per cluster × 67,092,469 clusters = 2,198,486,024,192 bytes (≈2,047 GB)]
[FAT32 maximum : 128 sectors per cluster × 33,550,325 clusters = 2,198,754,099,200 bytes (≈2,047 GB)]

See https://en.wikipedia.org/wiki/Design_of_the_FAT_file_system. for everything you ever wanted to know about the FAT filesystem.

You can see from the copied table that the maximum partition size is 2,047GB or ~2TB. You can have a 5TB drive and partition it off into a minimum of 3 partitions and use FAT32 on each partition as long as the largest partition is less than 2TB.

Does this answer the questions you have?

 

[Nikinp]

No not quite. I have drives that are smaller than 1tb and want to check if your advice was to upgrade to bigger than 1tb to have the native copying ability between win and OS X? If it’s not required I will just use the drives I have.

 

[Going Bald]

No not quite. I have drives that are smaller than 1tb and want to check if your advice was to upgrade to bigger than 1tb to have the native copying ability between win and OS X? If it’s not required I will just use the drives I have.

You can format any size drive down to ~32MB as FAT32. Less than that it is considered FAT16.
It is not necessary to upgrade drive size unless you need the storage space. I have a dozen or so 128GB laptop platter drives I use for temporary storage, connecting by USB-SATA adapter cable.

 

[edutun]

Hi Going Bald,
First of all very helpful and very thorough guide.
Big thank you!

I have a question about post-installation maintenance of the multiboot system.
What about (un)installing any additional software(especially in Win) and/or OS updates after the multiboot setup is configured and running?
Is there any special procedure for that?
Some disable/enable of CSM for example?
Or one can just do it like when it is a normal system with the exception that you need to chose the right OS in Clover bootloader at the beginning?

 

[Going Bald]

Hi Going Bald,
First of all very helpful and very thorough guide.
Big thank you!

I have a question about post-installation maintenance of the multiboot system.
What about (un)installing any additional software(especially in Win) and/or OS updates after the multiboot setup is configured and running?
Is there any special procedure for that?
Some disable/enable of CSM for example?
Or one can just do it like when it is a normal system with the exception that you need to chose the right OS in Clover bootloader at the beginning?

With Mac OS updates/upgrades there is no problem. With Windows updates I would suggest you either disconnect the SATA cable to the Mac drive and any other storage drives before updating Alternatively, if you can just disable the SATA port in UEFI/BIOS then do so without disconnecting the cables. Also, go into BIOS/UEFI and make the Win10 drive first in BBS boot order, so there is no problem booting it during the update process. Once updated, switch the BBS boot order back to the Mac drive and reattach the SATA cables/re-enable the SATA ports to restore the dual boot setup you had before.

 

[edutun]

With Mac OS updates/upgrades there is no problem. With Windows updates I would suggest you either disconnect the SATA cable to the Mac drive and any other storage drives before updating Alternatively, if you can just disable the SATA port in UEFI/BIOS then do so without disconnecting the cables. Also, go into BIOS/UEFI and make the Win10 drive first in BBS boot order, so there is no problem booting it during the update process. Once updated, switch the BBS boot order back to the Mac drive and reattach the SATA cables/re-enable the SATA ports to restore the dual boot setup you had before.

If that's all, perfect!
I'm buying this Icy Dock ExpressCage Series with 2x SATA/SAS SSD + 1x (Ultra) Slim ODD. Both of the SSD trays have power switch buttons so I suppose I can just switch off the macOS SSD when I need. Or it's mandatory to disconnect the SATA cable/port in UEFI/BIOS?

 

[Going Bald]

If that's all, perfect!
I'm buying this Icy Dock ExpressCage Series with 2x SATA/SAS SSD + 1x (Ultra) Slim ODD. Both of the SSD trays have power switch buttons so I suppose I can just switch off the macOS SSD when I need. Or it's mandatory to disconnect the SATA cable/port in UEFI/BIOS?

Turning off power to the drives works just as well. Will that dock take a laptop drive?

 

[edutun]

Turning off power to the drives works just as well. Will that dock take a laptop drive?

Well, the dock takes 2x 2.5'' SSDs so if the laptop's drive is the same form factor, sure.