this is indeed a MacOS issue. MacOS manages all volume mounts/unmounts, so we cannot work around it. What we have been doing is pressing for fixes for mounting/unmounting issues.

Is this for sure an Apple issue, or could we have a workaround for this?

This should have been fixed in Sonoma. It is Time Machine, it is "holding on" to the volume, after it is unmounted.

In terminal, you can see what is holding on, by unmounting, waiting a while, then entering this path (replace with your volume name, but temporarily remove spaces from the name, or this command is more complicated):

lsof /Volumes/myvolumename

and hit enter

But for a second magnetic disc raid formatted as APFS and used by Timemachine (seems Timemachine no longer works with HFS+ formatted drives), if I unmount it and disconnect the cable, Softraid reports "Volume Disappeared".

Sounds like there is a still a bug in either Softraid or Apple's Timemachine?

What terminal commands can I use to force Timemachine to unmount the drive so I can disconnect the cable without getting the "Volume Disappeared" message?

Thanks,
-Tony

They won't be removed from diskutil list, as they are connected, whether mounted or not.
this appears to be a Time Machine bug, where it is keeping open a volume that was closed (unmounted).

We may have to report this to Apple, but are reproducing it for engineering currently. If we can create a workaround, I can post it here.

When I use the command "sudo diskutil unmountDisk force disk#" to force eject all volumes as described earlier, I can see from Finder that they are unmounted, but when I call on "diskutil list" after unmounting all volumes, nothing has changed and they are all still listed.

Can you advise how I can get the volumes to be removed from diskutil list? if I could do that much I don't think I will have these "missing volumes" messages anymore.

Do you think my issue only pertains to whether there is both a HFS+ and APFS Volume present within the same thunderbay array?

Thanks for the continued support.

I think I may have found a way to duplicate your issue. I am entering it as a bug, but I think it is a Time Machine bug, in which case, we need to file it to Apple. I will reseach for a workaround in the meantime.

I hae been testing this on a couple machines and Time Machine is working correctly and I can unmount/disconnect without an error.

the diskutil list output is OK. You have the SoftRAID object (the volume), the APFS "Container" and the APFS published volume.

After I unmount the volume, I can enter this into terminal and the volume is not mounted:

ls /Volumes/

Same with you?

When I try as you suggested after a fresh reboot, diskutil returns:

mikeh@Michaels-MBP ~ % diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *2.0 TB     disk0
   1:                        EFI ⁨EFI⁩                     314.6 MB   disk0s1
   2:                 Apple_APFS ⁨Container disk1⁩         2.0 TB     disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +2.0 TB     disk1
                                 Physical Store disk0s2
   1:                APFS Volume ⁨Macintosh HD⁩            21.3 GB    disk1s1
   2:              APFS Snapshot ⁨com.apple.os.update-...⁩ 21.3 GB    disk1s1s1
   3:                APFS Volume ⁨Macintosh HD - Data⁩     808.7 GB   disk1s2
   4:                APFS Volume ⁨Preboot⁩                 338.4 MB   disk1s3
   5:                APFS Volume ⁨Recovery⁩                1.1 GB     disk1s4
   6:                APFS Volume ⁨VM⁩                      20.5 KB    disk1s5

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk2
   1: B6FA30DA-92D2-4A9A-96F1-871EC6486200 ⁨⁩              2.3 MB     disk2s1
   2: 2E313465-19B9-463F-8126-8A7993773801 ⁨⁩              7.3 MB     disk2s2
   3: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              2.9 TB     disk2s3
   4: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              1.1 TB     disk2s4
                    (free space)                         134.2 MB   -

/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk3
   1: B6FA30DA-92D2-4A9A-96F1-871EC6486200 ⁨⁩              2.3 MB     disk3s1
   2: 2E313465-19B9-463F-8126-8A7993773801 ⁨⁩              7.3 MB     disk3s2
   3: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              2.9 TB     disk3s3
   4: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              1.1 TB     disk3s4
                    (free space)                         134.2 MB   -

/dev/disk4 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk4
   1: B6FA30DA-92D2-4A9A-96F1-871EC6486200 ⁨⁩              2.3 MB     disk4s1
   2: 2E313465-19B9-463F-8126-8A7993773801 ⁨⁩              7.3 MB     disk4s2
   3: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              2.9 TB     disk4s3
   4: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              1.1 TB     disk4s4
                    (free space)                         134.2 MB   -

/dev/disk5 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk5
   1: B6FA30DA-92D2-4A9A-96F1-871EC6486200 ⁨⁩              2.3 MB     disk5s1
   2: 2E313465-19B9-463F-8126-8A7993773801 ⁨⁩              7.3 MB     disk5s2
   3: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              2.9 TB     disk5s3
   4: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              1.1 TB     disk5s4
                    (free space)                         134.2 MB   -

/dev/disk6 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk6
   1: B6FA30DA-92D2-4A9A-96F1-871EC6486200 ⁨⁩              2.3 MB     disk6s1
   2: 2E313465-19B9-463F-8126-8A7993773801 ⁨⁩              7.3 MB     disk6s2
   3: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              2.9 TB     disk6s3
   4: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              1.1 TB     disk6s4
                    (free space)                         134.2 MB   -

/dev/disk7 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk7
   1: B6FA30DA-92D2-4A9A-96F1-871EC6486200 ⁨⁩              2.3 MB     disk7s1
   2: 2E313465-19B9-463F-8126-8A7993773801 ⁨⁩              7.3 MB     disk7s2
   3: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              2.9 TB     disk7s3
   4: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              1.1 TB     disk7s4
                    (free space)                         134.2 MB   -

/dev/disk8 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk8
   1: B6FA30DA-92D2-4A9A-96F1-871EC6486200 ⁨⁩              2.3 MB     disk8s1
   2: 2E313465-19B9-463F-8126-8A7993773801 ⁨⁩              7.3 MB     disk8s2
   3: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              2.9 TB     disk8s3
   4: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              1.1 TB     disk8s4
                    (free space)                         134.2 MB   -

/dev/disk9 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *4.0 TB     disk9
   1: B6FA30DA-92D2-4A9A-96F1-871EC6486200 ⁨⁩              2.3 MB     disk9s1
   2: 2E313465-19B9-463F-8126-8A7993773801 ⁨⁩              7.3 MB     disk9s2
   3: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              2.9 TB     disk9s3
   4: FA709C7E-65B1-4593-BFD5-E71D61DE9B02 ⁨⁩              1.1 TB     disk9s4
                    (free space)                         134.2 MB   -

/dev/disk10 (virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Hibbard Thunderbay     +20.0 TB    disk10

/dev/disk11 (virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                 Apple_APFS                        +8.0 TB     disk11

/dev/disk12 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +8.0 TB     disk12
                                 Physical Store disk11
   1:                APFS Volume ⁨TimeMachine⁩             1.1 TB     disk12s1

mikeh@Michaels-MBP ~ % 

I don't know too much about this, but I think there are three disks associated with my Time Machine:

• disk11
• disk12
• disk12s1

After force ejecting these three disks in terminal with command "sudo diskutil unmountDisk force disk#" for all three of the disks mentioned in bullet points above (plus my 'Hibbard Thunderbay' HFS volume), I still get the same error messages from SoftRAID as I detailed in my first post of this thread.

Are you able to provide any insight?

Thanks for the continued support.

-Mike H

Restart your computer. Run this command in terminal:

diskutil list

Look at the list. How many instances of your Time Machine volume are listed?

If twice again, what if you use the force unmount on both numbers?

this is not permanent, just a check to see if this works.