Downgrading from Big Sur to Catalina

Started 3 months ago | Discussions thread
kierenlon
kierenlon Contributing Member • Posts: 974
Re: Stuck With Big Sur

Nick5 wrote:

kierenlon wrote:

HFS+ is best for hard disks (HDD)

The new APFS is designed to work best on SSD and may even be detrimental on a HDD

Since Mojave your OS Extended (Journaled) internal HDD on iMac 2017, 2019 Fusion Drive has converted to APFS from OS Extended Journaled. Also setting up new Time Machine external HDDLaCie Rugged as OS Extended Journaled and I have seven , will apply APFS automatically with Big Sur. When you set it up it says you applied OS Extended Journaled. Next time open your TM drive under INFO and you shall see APFS.

I didn't know that. It kind of makes sense for time machine as APFS has features for data consistency and a TM doesn't need to be fast. A fusion drive has an SSD for cache and probably normal disk cache too.

I don't think apple has sold a HDD mac for years, so I speculate is prompting the conversion for the consistency and new advanced filesystem features that the Mac OS might leverage.

Some of those features are going to make the disk head seek and skip around a bit more - something that a large HDD cache or Fusion Drive tries to eliminate by having a read/write buffer.

HFS+ at the moment is better for slow OS HDDs. That said, it's kind of moot, for OS drives, everyone really should try to migrate to solid state SSD / NVME and if needed, have data somewhere else if space per $£$ is a concern.

Some points here".
https://www.lifewire.com/apfs-on-different-disk-types-4155143

https://bombich.com/blog/2019/09/12/analysis-apfs-enumeration-performance-on-rotational-hard-drives

https://eshop.macsales.com/blog/43043-using-apfs-on-hdds-and-why-you-might-not-want-to/

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