AFPS or HFS+ for external USB3 HDD ?

[Dr. McKay]

I have a 2017 iMac with High Sierra and a 512Gb SSD, AFPS file system. I've got a USB3 external drive laying around that I would like to use for Time Machine and other backups (2Tb drive, would make 2 partitions, 1 for Time Machine, the other for all my other stuff.

I understand that AFPS is optimised for SSD and flash storage devices, so I assume that I'd better use HFS+ for the external drive ?

 

[jaybar]

Even if your external drive was SSD, if you wanted to format it as APFS, time machine would not work on an APFS formatted external drive.

 

[Fishrrman]

You want external drives to be HFS+.

HFS+ will still work fine with High Sierra or Mojave.
AND... you can take the external drive and connect it to a Mac (running an older OS) and still access it.

If you format an external drive to APFS, it will NOT be readable on older Macs running HFS+.

 

[jaybar]

Fisherman

I have an iMac 2017 with High Sierra. It has an SSD INTERMAL Drive. I have two external drives. If I format one external drive as APFS. and the other external as HFS+, then only the external formatted using HFS+ will run time machine. Why?

 

[chrfr]

Fisherman

I have an iMac 2017 with High Sierra. It has an SSD INTERMAL Drive. I have two external drives. If I format one external drive as APFS. and the other external as HFS+, then only the external formatted using HFS+ will run time machine. Why?

Time Machine is not supported on APFS volumes. APFS doesn't support what's known as hard links, which Time Machine requires.

 

[jaybar]

Time Machine is not supported on APFS volumes. APFS doesn't support what's known as hard links, which Time Machine requires.

Thanks