Samsung Portable SSD T7 not working with Catalina

Then use Mac OS Extended, Journaled. Are you sure your T7 is an SSD? What will you use the T7 for? Your image did not get uploaded.

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The drive should work just fine if you properly format it.

Drive Partition and Format - El Capitan or Later

1. Open Disk Utility in the Utilities folder.
2. After Disk Utility loads select the T7 drive (out-dented entry with Samsung.'s ID and size) from the side list. 
3. Click on the Erase button in the Disk Utility toolbar. A panel should drop down.
4. In the drop down panel set the partition scheme to GUID. Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
5. Click on the Apply/Erase button and click on the Done button when it is activated.
6. Quit Disk Utility.

No worries, I had this problem too and its an easy fix.

1. Open disk utility and select the drives top extension. Mine was labeled Samsung PSSD T7 Media.
2. Click "Erase" and when the pop up opens, rename your drive if desired, change the format to APFS, and the Scheme to GUID partition map, and then click erase.
3. Now the "Partition" icon will light up and you can partition the drive.

Good luck!

Format the drive HFS+. If that works OK, then use Disk Utility to convert it to APFS. Be sure you have set the Partition Scheme to GUID.

You need to go through some hoops when working with non-Mac formatted drives. This may be especially problematic if the new drive is formatted using NTFS to which macOS cannot write.

Norbert E. Fuchs wrote:

Thank you all for your help. After some input from Samsung Support it worked out OK. My problem is solved.

It is customary in public forums that when a solution is found the solution is posted in order to help others.

This is interesting and helpful information. I've always recommended not using third party disk management utilities and to use Disk Utility to manage a drive. I'll have to dig further into this.

Thanks for getting back with that info.

I recently obtained a 1 TB SSD T5 Samsung and a 2 TB SSD T7 Samsung, both external SSDs. They came formatted as Master Boot Record. I am running Catalina. I opened Disk Utility and selected Erase at the device (highest) level, selected GUID and APFS (all in one step, for the erase), and both are now APFS. I have used these to make bootable "clones" of my computer, running Catalina. The speed of the devices is extraordinary: the T5 reached 500 MB/s, and the T7 was close to 900 MB/s. The clone of my entire computer just took several minutes.

I suspect that the individual having trouble reformatting a T7 was sent a unit that was misconfigured by Samsung, leading to difficulties.

Which software did you download? There were multiple options. I downloaded the one that seemed obvious, Portable SSD Software 1.0 for Mac under Samsung T7, and I got PSSD V1.0, that does indeed turn on and off the security on the T7, but nothing that then allows me to us Disk Utility to partition and format as you describe.. just the same options that were available as before, namely exfat and OS extended.

Sorry, it. won't let me edit my original response ... the above instructions by Fuchs DO work, with the new PSSD software, IF you (and this is probably obvious to everyone but me) set the disk utility view option to show all devices (facepalms), Disk Utility > View>"show all device".

If you haven't solved this already. I let time machine do all the prep and stopped it before the backups began. Then when i went to Disk Utility the partition appeared. So it looks like Time Machine influences the Uid, this then allowed me to partition the Touch drive.

There was no input from Samsung. I remember getting frustrated that Disk Utility was not allowing for partitioning. So I let time machine do the work for me. Then I used Disk Utility successfully. In my case, that meant portioning half the drive for backup and half for general use.