APFS vs HFS backup with Time Machine on SSD

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APFS vs HFS backup with Time Machine on SSD

I just bought a 2TB SSD external drive and would like to use it for the first time to back up my iMac. I am currently running Mojave and am debating whether to back up before updating to Big Sur or after.

My Late 2014 iMac has a 1 TB Fusion Drive and Disk Utility tells me that it's formatted as APFS. From what I have read, it seems a major change in Big Sur is the support for APFS with Time Machine. However, I've also gleaned that APFS isn't great for Fusion Drives or SSDs because the data is stored in significantly more locations, putting stress on the physical components.

My questions then, are:

-Is it a good idea to use APFS with Fusion and SSD drives?

-If my current Fusion drive is formatted as APFS, can I store data on an external drive with Time Machine in HFS?

-Should I backup before switching to Big Sur or after?

-If I stick with HFS will I face issues in the future as APFS becomes more prevalent in Apple products?

iMac 27″, macOS 10.14

Posted on Jan 27, 2021 12:10 PM

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Answer 1

Barney-15E

Level 10

123,122 points

Jan 27, 2021 6:08 PM in response to Zoltan36

You should back up your Mojave Mac before you upgrade, and then after.

You need to have a backup before you upgrade.

When you complete the upgrade and everything is intact, I would erase the backup and let Big Sur format the Time Machine drive as APFS.

As far as I remember, you have to use Mac OS Extended (Journaled) for Time Machine in Mojave.

Is it a good idea to use APFS with Fusion and SSD drives?

Sure.

If my current Fusion drive is formatted as APFS, can I store data on an external drive with Time Machine in HFS?

Yes

Should I backup before switching to Big Sur or after?

Both.

If I stick with HFS will I face issues in the future as APFS becomes more prevalent in Apple products?

APFS is already as prevalent as it gets. iPhones and iPads have been APFS for a long time.

Big Sur uses APFS for Time Machine backups, if you don't already start from one on HFS+.

I'm not sure if you can install Big Sur on HFS+.

I think the only drawback would be that APFS must be shared out over SMB. If you have some reason to connect to that drive over AFP, you would not be able to do so if you format as APFS.

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Answer 2

Zoltan36 Author

Level 1

8 points

Jan 28, 2021 9:31 AM in response to Barney-15E

That's a lot more clear. I don't have to work with networks or servers so APFS seems the right way to go.

My last concern is the one about using APFS on an HDD. Speed isn't really that important to me: I'll only be doing periodic backups, perhaps once a month. Rather the way APFS stores in many tiny blocks seems like it could break the SSD. But barring a hardware failure on my external I'm all for APFS!

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Answer 3

Barney-15E

Level 10

123,122 points

Jan 28, 2021 9:52 AM in response to Zoltan36

I'm not aware of any block size difference with APFS. I don't think the OS or file system has any control of where items are stored on an SSD. The drive controller should be handling that. It really doesn't matter where parts of files are stored on an SSD. Read access speed is the same wherever they are located. With a spinning HDD, that is a much different consideration.

I don't think APFS has broken any iPhone or iPad storage. They have been using APFS for a long time.

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APFS vs HFS backup with Time Machine on SSD

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