Samsung T5 SSD will not erase

If you are using the Samsung proprietary software to manage the drive, then perhaps that software is either locking the drive or it is encrypting the drive. Make sure the Samsung software does not have a lock on the drive and if the drive is encrypted, then make sure the drive encryption is unlocked before you attempt to erase the drive. It is best to have the Samsung software reset the drive's settings to default and to disable encryption if encryption is currently enabled. Then uninstall the Samsung software by following the developer's instructions. If you want the drive to be encrypted, then you can have macOS encrypt the drive or you can use VeraCrypt a third party app with cross-platform support. If the external drive supports hardware encryption, that is a nice feature, but relying on a proprietary app to control it is risky.

Within Disk Utility click "View" and select "Show All Devices" so that the physical drives appear on the left pane of Disk Utility. Select the physical drive and erase it as you described: GUID partition and MacOS Extended (Journaled).

If you still get an error, then immediately try to erase the whole physical drive again. I've encountered some scenarios where the first attempt to erase a drive will fail, but the second attempt will succeed. I have no idea why.

somersetshire wrote:

Thanks for the reply.

I originally used the T5 in a MB Air. I had a Samsung password for it.

This tells me the Samsung drive is most likely hardware encrypted or at least locked by the Samsung software. Once you use the Samsung software to disable the lock or disable the hardware encryption, then you should be able to use Disk Utility to erase the drive as described in my other post and use the Samsung drive as a TM backup drive. Although if you are using this a TM drive for an M1 Mac, then you will most likely need to erase the drive as GUID partition and APFS (top option) since I believe macOS 11.x+ now prefers to use the APFS file system for TM.

I've never used the Samsung T5 SSD nor used the Samsung software so I cannot really advise you on specifics here. Maybe you will need to use an older Intel Mac or a Windows PC where you can actually install & use the Samsung proprietary software to disable the hardware encryption on the Samsung SSD.

Here is a link to the Samsung T5 SSD user's guide:

https://www.samsung.com/semiconductor/global.semi.static/Samsung_Portable_SSD_T5_User_Manual_English_1.2.pdf

Here is the general product page which also includes access to the Samsung proprietary software:

https://www.samsung.com/semiconductor/minisite/ssd/product/portable/t5/

I believe beginning with Big Sur macOS now prefers to have TM drives formatted as GUID partition and APFS (top option). Sorry, but I cannot find any current Apple articles with the details since it appears Apple has removed any easy to find references to the preferred file system for a TM backup drive. The closest reference I have found is that TM will prompt you to erase the drive if necessary. Personally I try to avoid the APFS file system when possible since it seems to become corrupted so easily and cannot be repaired by First Aid, but I think APFS is what you should probably use as Apple may force it on you at some point if it is not already forced on you when creating a new backup drive.