Why You Should Always Use HFS+ to Format Mac Hard Disk Drives

SSDs are currently the fair-haired children of computer storage, but the real work-horses (to mix metaphors) are hard disk drives. They hold more, last longer, and cost far less per megabyte.

I’ve always “known” that HFS+, also called “Mac OS Extended,” is better for formatting spinning hard drives for the Mac  than APFS. But, I wondered, is that just hearsay or is there some truth to it?

So, during my recent performance testing of an OWC Thunderbay 4 HDD RAID, I put this to a detailed test.

NOTE: HFS+ is a hard drive format, invented by Apple many, many years ago, for hard disk drives. APFS, also invented by Apple, is a newer format specifically designed for SSDs.

The short answer: HFS+ (Journaled) is absolutely the best choice for formatting spinning media (traditional hard disk drives). This performance benefit becomes especially pronounced when creating RAIDs.

NOTE  Journaling is the process of tracking data changes made to a hard disk that have not yet been fully stored, because saving or erasing data is a multi-step process. In the event of a system crash or power failure, journaled hard disks can be brought back more quickly with a lower likelihood of becoming corrupted.

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For my tests, I set the speed of an HFS+ formatted drive or RAID to 100% (the green line at the top). Then, I measured the speed of the same configuration formatted using APFS.

In all cases, the APFS-formatted drive was slower. Dramatically slower as the number of drives increase. For example, read speeds for a 4-drive RAID 0 were cut in half! The percentage number at the top of each bar indicates the speed of APFS for that test compared to HFS+.

NOTE: Because APFS affects individual disk performance, you would see these same performance drops whether you format the RAID as RAID 0, 4, 5, or 1+0; though the amount of slow-down will vary.

When formatting a new HDD (hard disk drive) using Disk Utility, select Mac OS Extended (Journaled), which is the current name for HFS+, to get the best performance, meaning read and write speeds, out of your gear.

To determine how your storage is formatted, open Utilities > Disk Utility and select the drive from the sidebar on the left. The text under the name of the drive describes its format. (In the screen shot above, the “Webinar Archives” drive is formatted using HFS+.)

NOTE: If you discover that you formatted your drive incorrectly, you must FIRST copy all data off it before you reformat. Reformatting will erase all existing data on the drive or RAID.

EXTRA CREDIT

• This PDF contains the results of all my tests, if you want the details.
• Read this article to see almost a dozen performance tests for this HDD RAID.