How to Erase the Partition Table?

I'm trying to put back into TM-BU service a 4TB external HD (disc, not SSD). For a short while it was used by TM, then shelved, then used to copy another HD. So there are two partitions, and neither DiscUtility or TechToolPro will let me do anything more than initialize each volume. But I can't treat the disc as one volume.


I could also have a friend with a PC do it, so I'm looking for one. But in the meantime:

mac Mini 7,1 — OS 11.7.10


TIA


Posted on Jan 10, 2025 12:03 PM

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9 replies

Jan 10, 2025 01:33 PM in response to mrbl

• Launch Disk Utility.

• In DU's menu bar select View > Show All Devices

• Select the topmost icon for the device you want to erase - not any indented volume below it - and then click the Erase button.

• Select GUID Partition Map for the Scheme, select APFS as the Format and supply a Name. Then click Erase.


Erase and reformat a storage device in Disk Utility on Mac - Apple Support


Jan 11, 2025 09:57 AM in response to mrbl

The problem as I see it is not with the WD drive.


It appears that TM is having a problem because the internal drive "Untitled - Data" is nearly full. There is not enough space for TM to do what it needs to do.


Please provide Disk Utility screen shots for the volumes "BugSour" and "Untitled - Data"


I suspect you're going to have to offload some of our user data and free up some space. Generally speaking, you should always maintain a minimum of 10% of the startup drive's capacity as free space.

Jan 10, 2025 05:40 PM in response to D.I. Johnson

Thanks for staying with me, D.I. The red/blue disappeared a while back, but now it's a TM problem



At this point, TM thinks the disc is completely filled. And it's confused about the disc's name

What's more, when preparing the disc for TM use, it thinks BUbig is both a disc already set up AND one available as another TM disc:

DU is fine with the disc, and a Finder Get-Info also says it's empty


This has survived numerous erase/reformats, as well as TM set-ups. When it's just a plan disc, I can write to it fine.

Maybe I should move this puzzle to a discussion area specific to TM. But I'm glad you're willing to take a look at it.

Jan 11, 2025 09:07 AM in response to D.I. Johnson

That's what it looks like:


At this point , in TM SysPrefs, I also tried:

1.) "Select BU Disc" = back to the double "BUbig" appearance loop, right through to the " 'Untitled Data' is nearly full"


I remember back in OSX, one could delete a borked "prefs" file. Is there anything like that in OS11? DU is behaving fine, but TM is behaving borked.

Jan 11, 2025 06:41 PM in response to D.I. Johnson

Exactly it. ~1% free space, and at one point Mail was unable to display any mailboxes. Figuring out what to move/dump wasn't hard, and I'm now at 30% free. I could get another 20% if by archiving many years of email on to MyBork. I'm now 25% of the way through the initial BU without a hitch.


Thanks for mitigating my crisis <G>

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How to Erase the Partition Table?

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