HDD RAID for Time Machine backups – APFS or HFS + encrypted or not?

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Level 1

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HDD RAID for Time Machine backups – APFS or HFS + encrypted or not?

I recently acquired a 2-drive HDD RAID I'd like to use in RAID-1 for Time Machine backups of an iMac whose APFS-formatted Fusion drive is FileVault encrypted. Two questions somewhat related to this thread: https://discussions.apple.com/thread/252536795

1.) Previously, APFS was not recommended for HDD formatting. Today, with macOS 11.5, is that still the case? Does that apply equally to single-HDD applications as well as RAID (specifically RAID-1)? Are there any security/performance pros/cons to consider between APFS and Mac OS Extended when formatting an HDD RAID that will be used for Time Machine backups?

2.) When Time Machine backs up an encrypted drive, are the backup files already encrypted by default, or are they unencrypted while being backed up to an unencrypted drive? I'm trying to weigh the pros and cons of encrypting the Time Machine backups.

iMac 27″ 5K, macOS 10.15

Posted on Aug 1, 2021 9:38 AM

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Answer 1

Lissy_12

Community Specialist

Aug 2, 2021 8:48 AM in response to mc-smo

Hi,

We understand you have a question about encrypted backups. We would recommend the following resources that can help:

Keep your Time Machine backup disk for Mac secure

Choose a backup disk and set encryption options on Mac

Hope this helps!

Have a great day.

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Answer 2

mc-smo Author

Level 1

8 points

Aug 2, 2021 10:09 AM in response to Lissy_12

Thank you for your response.

Yes, I did read those kdb articles. The first implies Time Machine backups to an unencrypted disk (regardless whether from an encrypted or unencrypted source?) are themselves unencrypted. So I assume they are being unencrypted from the source during the TM backup process.

I'm not finding anything about HDD RAID-1 TM backup disk formatting, and whether APFS is recommended. I think it's both a question of SSD vs HDD as well as single-disk versus RAID-1. This article implies APFS when starting fresh, but I'm still not finding anything about APFS formatting of a RAID.

https://support.apple.com/guide/mac-help/types-of-disks-you-can-use-with-time-machine-mh15139/11.0/mac/11.0

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Answer 3

Lissy_12

Community Specialist

Aug 3, 2021 6:17 AM in response to mc-smo

mc-smo,

Thank you for clarifying. As noted in the additional resource below "APFS or APFS Encrypted disks are the preferred format for a Time Machine backup disk. If you select a new backup disk that’s not already formatted as an APFS disk, you get the option to erase and reformat it. ":

Types of disks you can use with Time Machine on Mac

Hope this helps!

Have a great day.

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Answer 4

mc-smo Author

Level 1

8 points

Aug 3, 2021 11:43 AM in response to Lissy_12

Yep, I read that as well noting the statement: "Time Machine still supports backups on Mac OS Extended format (Journaled), Mac OS Extended (Case-sensitive, Journaled), and Xsan formatted disks."

The reason I raised this issue is hoping for guidance from within the community regarding current use of APFS with HDDs. This piece, though nearly 4 years old, raises some issues which apparently have not been resolved: https://eshop.macsales.com/blog/43043-using-apfs-on-hdds-and-why-you-might-not-want-to

Hoping someone might have insights into current best practices wrt formatting HDD RAID-1 for primary use as (encrypted) Time Machine backup disk.

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HDD RAID for Time Machine backups – APFS or HFS + encrypted or not?

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