Formatting secondary harddrive APFS

Hello khaidir77,

There is no need to reformat it. If you do, it may be unreadable by older versions of the operating system or other operating systems. If that is not an issue, then you can certainly reformat it. I think you would have to use some command line tool to convert it. You could erase and reformat it as APFS. In either case, make sure you have a backup and the backup isn't using APFS.

This is a question of if you 'should'. That's up to you.

There are benefits of the new file protocol, but also it's less compatible with older systems. So if you want to use that drive for Time Machine, or if you use the old hard links on that drive, or if you want that drive to work on pre-high sierra systems then leave it with the old format.

But if those cases don't apply, then go ahead and upgrade and get the benefits of the new system.

Personally, I would not convert any external drive with any important

and irreplaceable data on it for a while yet. Until APFS gets some milage

on it from several million users, there is no telling what little foibles may

be in hiding.

HDD's can be formatted APFS but Apple do not advocate it. The installer will not format HDD's or Fusion Drives to it.

I did once clone an HDD formatted as APFS. It took thirty minutes to boot and about one minute between trackpad clicks. Losing patience and clicking again increased that to two minutes. Powering off left the computer unblessed and it needed mounting in DU. So don't try it on a boot volume... just don't.

Can you please explain where apple doesn't recommend converting hdds?

From what I'm reading they do say it works:

https://developer.apple.com/library/content/documentation/FileManagement/Concept ual/APFS_Guide/FAQ/FAQ.html#//apple_ref/doc/uid/TP40016999-CH6-DontLinkElementI D _17

Yes. Apple File System is optimized for Flash/SSD storage, but can also be used with traditional hard disk drives (HDD) and external, direct-attached storage.

What I don't see is apple recommendation for bootable hdds. Just external drives.

Your situation is a bootable drive which is totally different than an external drive.

Nevertheless There are other users who said after reinstalling Mac os apfs works fine on a hdd

My understanding is that mechanical hard drives can not be formatted as APFS volumes. APFS is currently only supported on SSDs.

I am sure the same principal applies, if it is HDD, keep it as HFS+ for now.

I see no reason why a secondary internal drive would be any different than an external one. The main issue is of you want to convert your boot drive hdd. That seems to cause some issues for certain users.

However a secondary hdd is not something apple does often so they may not have an official response about this for a while if ever.

You may want to check with the manufacturer. Sshd is a hdd with some flash storage built in and is managed by firmware on the hard drive not by Apple.

Apple has confirmed that fusion drives don't work yet but will in a future update. But that's totally different than what you are talking about. No idea what an Sshd would do, but I don't see why it would be ok.

Test at your own risk.

Yes, I should have said APFS is not yet ready for HDD boot drives. My example was an external HDD, cloned using Carbon Copy Cloner. Not helped by a USB-A connection. I now use two Samsung T5 SSD's with APFS Encrypted, for my clones, which are a vast improvement.

https://bombich.com

Devices formatted as Mac OS Extended (HFS+) can be read from and written to by devices formatted as APFS.

Prepare for APFS in macOS High Sierra - Apple Support