Reliably using HFS+ Format on MacOS 26.1 Tahoe and later...

Drive Utility incorrectly says the drive has failed when using Disk First Aid, the indication is 'error 08'. I believe this is an incorrect report as reformatting with APFS checks out perfectly fine and it was clear on examination of the drive that it had been changed by the OS to Read-Only and not changeable back to R/W in any settings I could find.

Unfortunately, no it won't. The original use case format was HFS+ Journaled and the failure in Tahoe after it had previously been formatted and worked for awhile rendered the disk Read-Only and there was no way I found to able to to convert it to APFS without reformatting. I blame Tahoe 26.0.1 ->26.1 update release for it as that was the last interaction of OS to attached media before it happened, but I can't prove it. Wasn't aware of the problem until my backup program failed to backup using that destination (CCC). Then another drive showed as failed and then a third - all happened to be that format. Then DU (Disk Utility) said that the drive could not be repaired with 'Error code 08' when I tried that. Basically down the rabbit hole I went.

It was only after perusing other reports that I realized that Tahoe had and continues to have issues with HFS+, this is a specific and unique one, though. It I obviously repeatable and hopefully someone at Apple will be able to shed light on why and maybe a fix it. I can see if a new format would result in an error, but an existing drive failing in whatever previous format failing with not notice seems pretty bad.

Yep. My Mac Mini is functioning as a backup server using JBOD's directly attached as remote redundant destinations for 3 Macs on the local net. 3-8TB ea. x12.

When will Apple signal that HFS+ (especially its variants as in my example) should not be used, e.g. unsupported or completely deprecated? Luckily for me, the number of HDD's with HFS+ has just shrunken, of necessity. While it was extended to degree as you said by the inability to convert a drive that has got read-only to APFS. The overhead required to copy TB-size devices and time required to restore to an APFS formatted device is extensive, so it seems that some workarounds may be an advantage and/or getting the word out here about possible anomalies should be undertaken.

What happened to me in my recent experience with warnings in DU and elsewhere on these pages, indicates to me that HFS+ formatting and Tahoe do not mix well.

Industry notices of its full deprecation (E.G, lack of support) being imminent support that view. Caveat emptor.

HenryS wrote:

My specific issue occurs when using PREVIOUSLY formatted (HFS+ Extended Journaled) format drives in Tahoe 26.1. The result was after several weeks of use after upgrade to 26.1 (from 26.0.1 in fact) several JBOD disks on my MacMini went into read-only mode where they were no longer writeable!!

Three failed drives were all no longer repairable in Disk Utility (error 08 failure to fix in First Aid)!

My only alternative to this failure of the backup drives was to migrate off any data from the Read-only drives (one at a time, reformat to APFS (not encrypted) and restore the data. This is an incredibly bad outcome with no report of problems in Tahoe until it just magically happens. ARRRRGGGGHHHH.

Will have to reformat all my HFS+ drives in this way that aren't already formatted if used in Tahoe past version 26.0.

Plot twist to upgrading? Or just boo-boo since it seems only to affect previously HFS+ Extended, Journaled formatted drives! Neither show full 100% backwards compatibility in Tahoe, though.

HenryS wrote:

My specific issue occurs when using PREVIOUSLY formatted (HFS+ Extended Journaled) format drives in Tahoe 26.1. The result was after several weeks of use after upgrade to 26.1 (from 26.0.1 in fact) several JBOD disks on my MacMini went into read-only mode where they were no longer writeable!!

Three failed drives were all no longer repairable in Disk Utility (error 08 failure to fix in First Aid)!

My only alternative to this failure of the backup drives was to migrate off any data from the Read-only drives (one at a time, reformat to APFS (not encrypted) and restore the data. This is an incredibly bad outcome with no report of problems in Tahoe until it just magically happens. ARRRRGGGGHHHH.

Will have to reformat all my HFS+ drives in this way that aren't already formatted if used in Tahoe past version 26.0.

Plot twist to upgrading? Or just boo-boo since it seems only to affect previously HFS+ Extended, Journaled formatted drives! Neither show full 100% backwards compatibility in Tahoe, though.

The drives were physically fine, I should point out, after reformatting in APFS (either encrypted or other variants) and device checks confirm this as to lack of defects. As has been pointed out DU has no such tools.