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iRock1

macrumors 65816
Original poster
Apr 23, 2011
1,081
144
Hi,

I have an external enclosure containing five WD Red of 2 TB WD each. They are set in RAID5 making it virtually one external drive.

Then I have split this 'one' drive in two partitions — one is a 6.5 TB partition formatted in 'MacOS Extended (Journal)' and used for media, while the other is a 1.5 TB partition formatted in 'MacOS Extended (Journal, Encrypted)' used for Time Machine.

I was wondering if it would be recommendable upgrading the Time Machine partition to the more modern APFS while leaving the partition used for media untouched.

Also worth noticing that I'm using a 2009 iMac with 10.13 High Sierra and two internal drives — one is an SSD of 500 GB (which is split in two partitions — one in APFS for macOS and the other in NTFS for Windows) and the other is a separate 7200 rpm WD disk of 1 TB installed in the SuperDrive bay.

I appreciate your guidance!
 
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MacCheetah3

macrumors 68020
Nov 14, 2003
2,169
1,132
Central MN
I can't think of a reason why you couldn't -- although, I haven't tried/done it.

Nevertheless, for your specific use case, I would suggest not to use APFS on your RAID because...
Macworld said:
While APFS has advantages for SSD-based storage, there really aren’t any for hard disk drives, the most likely kind of drive used for large-capacity backup drives. I would set up any new Time Machine volume formatted with APFS, but not convert an old one from HFS+.

Basically, APFS was designed with the characteristics of SSDs specifically in mind -- which is indeed why it was originally only allowed, supported on SSDs.
 
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iRock1

macrumors 65816
Original poster
Apr 23, 2011
1,081
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I can't think of a reason why you couldn't -- although, I haven't tried/done it.

Nevertheless, for your specific use case, I would suggest not to use APFS on your RAID because...


Basically, APFS was designed with the characteristics of SSDs specifically in mind -- which is indeed why it was originally only allowed, supported on SSDs.
Well, thanks to that article, I've just learned that I couldn't format that Time Machine partition in APFS even if I wanted, since Big Sur is the bare minimum. ¯\_(ツ)_/¯
 

Fishrrman

macrumors Penryn
Feb 20, 2009
28,630
12,751
I'd recommend that you do not use "a partition" for a time machine backup.
Instead, maintain that on a SEPARATE drive dedicated for that purpose only.
 
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iRock1

macrumors 65816
Original poster
Apr 23, 2011
1,081
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FWIW, on my hackintosh I have a 2TB mechanical HD with a APFS partition (for a clone of my Mojave system) and an HFS+ partition with some data on it.

Good to know that they can live together if necessary!

I'd recommend that you do not use "a partition" for a time machine backup.
Instead, maintain that on a SEPARATE drive dedicated for that purpose only.

Is there a strong argument for that?
 

Nguyen Duc Hieu

macrumors 68030
Jul 5, 2020
2,914
959
Ho Chi Minh City, Vietnam
Yesterday I did some experiments with the SSD on my late 2009 iMac

1. HFS and APFS on the same SSD
I had to make 2 physical partitions: 1 for HFS and one for APFS
The HFS partition is on the head of the SSD. It was created first, with the purpose to install High Sierra from sratch to switch the iMac to Target Display Mode when I need a monitor.
The APFS partition I intent to clone a patched Catalina disk (from another machine) as mainly use OS.

This arrangement looks clearer to me as 2 separated partitions are visible in the Partion Windows.
I'll try installing OS on both partions to see if they work smoothly.

2. 2 APFS volumes on the same SSD

I tried this first but it confused me because of the size displayed on Disk Utility. Thus I deleted them both.

I supposed that's how APFS works on SSD: The OS doesn't divide the SSD physically, and data bit are writed randomly on the SSD, thus help keeping the SSD last longer.
 

chabig

macrumors G4
Sep 6, 2002
11,320
9,011
Is there a strong argument for that?
His argument is based on purpose. If you're using a drive for backup, then it makes no sense to also store data on that drive unless you're willing to lose it to a drive failure. The way you've got things set up, you'll lose both your backups and your media if something happens to your RAID. Where is your media backed up?
 
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