Slow T7 SSD on macOS Sonoma - Magician not recognising external SSDs

[andrewbt]

Hi, I'm running Sonoma 14.5 on a recent M2 MacBook Air and getting 3MB/s write speed on my Samsung T7 Shield (format APFS Encrypted).  

Using the same Thunderbolt 4 cable I'm getting 360MB/s write on an old Samsung T3 drive and 2300 MB/s on an external NVME drive, so I don't think it's a cable problem.  Apple's disk utility didn't find any problems on the T7.

I installed Samsung Magician to see if that might identify the issue but neither the T3 or T7 drive show up (however the NVME drive does).

Any ideas on what the issue might be with the T7 drive or Samsung Magician?

Thanks, Andrew

[TechZilla]

Have you formatted it correctly for usage on your Mac?

[andrewbt]

Yes, should have mentioned that. It’s APFS formatted. 

[TechZilla]

Have you tried formatting it as ExFat?

[andrewbt]

No. Odd that bit doesn’t show up in Samsung Magician too. 

[koveraasen]

Were you able to solve this? I have the exact same problem with my T7 Shield. Using an encrypted APFS volume. Has been working fine for some time, but noticed today that the write speeds were extremely slow (2-3MB/s). Reads seems OK.  

Tried several cables and three different Mac's (both M1 Air, Intel MBP and an older Mac Mini - all with different versions of MacOS). Same result on all tests.

Also tried to upgrade the T7 FW to the latest version using Samsung Magician, but it did not do improve anything.

The disk was about 75% full. Tried deleting some stuff to get it below 50%, but still no improvements.

The disk is pretty much useless in the current condition. Is it broken?

[andrewbt]

I didn’t solve it. Just bought a new drive - Crucial X9 - which was good value, higher capacity and speed which is the norm with drives. Hope to have more luck with this and if not then maybe at least get some support

Luckily my content is duplicated and I’ll do a long copy off the T7 one weekend or something onto the new drive. Hope you sort yours out. 

[alexcronin]

I am having the same issue with a T7 Shield formatted with APFS encrypted I was wondering if you resolved it?

[alexcronin]

Solution:

 **Warning** firmware updates on encrypted devices may cause data integrity issues. The actions taken below did not cause this

External Harddrive: Samsung T7 Shield APFS Volume • APFS (Case-sensitive, Encrypted)
OS: MacOS 15.2

Actions taken on MacBook Pro M1 and Windows

Mac

- Samsung Magician (version 8.2.0) was not displaying the external SSD (samsung T7).
- Blackmagic Disk Speed Test (https://apps.apple.com/us/app/blackmagic-disk-speed-test/id425264550?mt=12) was started displaying a write speed of approx 4MB/s, this test was abandoned.
- A 5GB iso was attempted to be written and a write time of > 40 mins was indicated

Windows Machine

- Samsung Magician version 8.2.0.880 was installed
- T7 Shield was detected
- `New Portable SSD` window was displayed with options to choose `Security Mode` .`cancel`  was pressed as it might reformat the disk if any option was selected. (This is a guess)
- In bottom right `update` was pressed to determine if firmware update was available
- Update was applied and new version `FXI72P2Q_3603_02000101` was applied.
- Disk was unmounted 

Mac

- Blackmagic `Disk Speed Test` was started and displayed 4Mbps approx and then was abandonned
- 5GB iso was manually tested and transfered in approx 2 mins - indicated success
- Blackmagic app was uninstalled and reinstalled as it was believed that incompleted tests or other factors may have given a false slow read on the retest
- Blackmagic `Disk Speed Test` was uninstalled (deleted from the Applicaitons folder)
- Mac was shutdown and restarted
- Blackmagic `Disk Speed Test` was installed via APPs store and the disk retested scoring > 800MB/s write and > 750MB/s read
- I considered this result and the iso write time of 2 mins as a successful outcome

Cause of the issue
- unknown, perhaps an issue related to an upgrade from MacOS 14 to version 15

[koveraasen]

No, ended up getting another brand drive. Formatted the T7 and only using it for non-important stuff. Has been working ok after that, but without encryption.