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Slow external drive on Sequoia 15.2

vs40

vs40

macrumors member
Original poster
Jan 9, 2016
79
85
Hi folks!
After updating my MBA M1 to Sequoia 15.2 (24C101) I have very slow write speed on my external SSD(Samsung T7 Shield).
Write speed is slower than an old HDD.
I thought my drive is dying, but it has normal speed with Windows laptop and Samsung app shows good health status.
Any ideas?

SCR-20241217-olrl.png
 
You aren't the only one who has seen this problem.

I have two Samsung t7 "shield" drives (each 1tb) and they exhibit the problem.

Typically, when I first connect the drive, and try a speedtest on it (before doing anything else), it will offer up fast read speeds, but write speeds are TERRIBLE (as seen in the OP's post above). Both my drives are formatted HFS+.

Here's an "AJA System Test Lite" reading I just recorded while composing this reply:
AJA 1.jpg


There's SOMETHING -- whether it be in the drive's circuitry, or elsewhere -- that is failing to establish proper communication speeds with the Mac when first connected.

I happen to have an old copy of Drive Genius, and it offers "repair" and "rebuild" options for drives (the latter being a modest "directory rebuild", not sure?).

I opened DG3, and ran the rebuild option on the drive.
Here are the results:
===============
Repairing volume...
Checking Journaled HFS Plus volume.
The volume name is t7 Movie & TV Archive
Checking extents overflow file.
Checking catalog file.
Checking multi-linked files.
Checking catalog hierarchy.
Checking extended attributes file.
Checking volume bitmap.
Checking volume information.
The volume t7 Movie & TV Archive appears to be OK.
Rebuilding volume...
Checking Journaled HFS Plus volume.
The volume name is t7 Movie & TV Archive
Checking extents overflow file.
Checking catalog file.
Rebuilding catalog B-tree.
Rechecking volume.
Checking Journaled HFS Plus volume.
The volume name is t7 Movie & TV Archive
Checking extents overflow file.
Checking catalog file.
Checking multi-linked files.
Checking catalog hierarchy.
Checking extended attributes file.
Checking volume bitmap.
Checking volume information.
Invalid volume file count
(It should be 1338 instead of 1316)
Invalid volume directory count
(It should be 271 instead of 270)
Invalid volume free block count
(It should be 106642522 instead of 106838533)
Volume header needs minor repair
Repairing volume.
Rechecking volume.
Checking Journaled HFS Plus volume.
The volume name is t7 Movie & TV Archive
Checking extents overflow file.
Checking catalog file.
Checking multi-linked files.
Checking catalog hierarchy.
Checking extended attributes file.
Checking volume bitmap.
Checking volume information.
The volume t7 Movie & TV Archive was repaired successfully.
Verifying volume...
Checking Journaled HFS Plus volume.
The volume name is t7 Movie & TV Archive
Checking extents overflow file.
Checking catalog file.
Checking multi-linked files.
Checking catalog hierarchy.
Checking extended attributes file.
Checking volume bitmap.
Checking volume information.
The volume t7 Movie & TV Archive appears to be OK.
===============

Note the following that was found:
"Invalid volume file count
(It should be 1338 instead of 1316)
Invalid volume directory count
(It should be 271 instead of 270)
Invalid volume free block count
(It should be 106642522 instead of 106838533)
Volume header needs minor repair
Repairing volume."

But... over the course of months... the problem will "be back" each time I connect the drive. The "fix" doesn't "stick".

HAVING SAID ALL THAT...
I've found that if you "plow through" -- that is, cancel and then restart the test several times -- the write speeds will suddenly "jump upwards" to where they SHOULD be.

Here's what happened if I stopped, and then restarted the AJA test 3 or 4 times:
AJA 2.jpg


Not sure if this matters with APFS formatted drives or not.
My other t7 has a single APFS partition on it, but it's not near at the moment.

My advice to the OP:
Try AJA System Test Lite (free)
or
Try Blackmagic Disk Speed Test.

If the initial write result is bad, stop and restart the test.
Repeat this about 4-5 times.
See if the write speeds suddenly "break through" and jump up to where they should be...
 
Fishrrman said:
If the initial write result is bad, stop and restart the test.
Repeat this about 4-5 times.
See if the write speeds suddenly "break through" and jump up to where they should be...
Click to expand...
You are right, after few iterations speeds are normal again, but it's not a solution for me.
I use my external drive for quick file download/transfer and I can't do those rituals every time to bring performance back.
According to some user-reports last macOS version with proper external drive behavior was Monterey.
If I don't find proper solution till weekend, I might downgrade from Sequoia.
 
vs40 said:
You are right, after few iterations speeds are normal again, but it's not a solution for me.
I use my external drive for quick file download/transfer and I can't do those rituals every time to bring performance back.
According to some user-reports last macOS version with proper external drive behavior was Monterey.
If I don't find proper solution till weekend, I might downgrade from Sequoia.
Click to expand...
I would at least start by installing Samsung Magician and checking the disk for firmware updates. I’m not clear if you did that step in Samsung app when you checked the drive already. I’d also suggest trying a different cable and also physically moving the drive somewhat to make sure you’re not getting some sort of interference.
What format are these drives? The errors in post 2 of the thread are typical of disks formatted as HFS+/MacOS Extended, and there’s really not any great reason to keep using that format anymore as it’s much less robust than APFS is.
 
chrfr said:
I would at least start by installing Samsung Magician and checking the disk for firmware updates. I’m not clear if you did that step in Samsung app when you checked the drive already. I’d also suggest trying a different cable and also physically moving the drive somewhat to make sure you’re not getting some sort of interference.
Click to expand...
All those steps are already done, but no results.

chrfr said:
What format are these drives? The errors in post 2 of the thread are typical of disks formatted as HFS+/MacOS Extended
Click to expand...
Post 2 is from another user, not from me.
All my drives are exFAT, because I need cross platform support.
And I have this problem only with MBA Sequoia.
 
OP wrote:
"According to some user-reports last macOS version with proper external drive behavior was Monterey.
If I don't find proper solution till weekend, I might downgrade from Sequoia."

I don't believe that the "OS version" has anything to do with the problem with the t7 SSDs.

All the tests I performed in reply 2 above were on a 2018 Mini (Intel) still running OS 10.14.6 "Mojave".

It's "in the drive" -- NOT the OS.

For this reason, I can no longer recommend Samsung t7 "shield" drives.
There's a problem with them that Samsung (to my knowledge) won't fix.

These days, I recommend the Crucial X9 (USB3.1 gen2). Offers up good speeds from the moment it's connected...

chrfr chimes in with:
"I would at least start by installing Samsung Magician"

UGH.
That's what I tried last night (on my 2021 MacBook Pro 14").
Awful, AWFUL software.

So then, I tried to remove it -- you can't get rid of it.
It put an icon into the dock that couldn't be removed through normal procedures.

I finally used EasyFind to locate all the pieces, and managed to delete them one-by-one.

Final thoughts on Samsung drives:
They're to be avoided.
I've seen many reports from forum members having trouble with Samsung drives, either the nvme format drives, or -- like now -- with the external SSDs.

I'll use other drives in the future...
 
Last edited:
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I stumbled over the same problem yesterday...!

My T7 Shield (2TB) now show write speeds in the range of 3-6 MB/s. I didn't use them for a long time, before (w/ MAC OS Ventura) they showed speeds around 600-800 MB/s, now with MAC OS Sequoia they show these slow speeds, all 4 disks I have.

The funny think: My normal Samsung T7 with 2TB still show speeds around 600-800 MB/s. Really weird!

Updating the firmware didn't change anything.

Any more ideas? What alternatives are recommended?

Herbert
 
I just checked my T7 shield 2tb with black magic. On 15.2, I lost 50+MB/s off both read and write speed. I run the speed test periodically to double check the health of the drive
 
Really weird...!

After doing some more tests, and nothing really worked, I finally decided to erase on of my T7 Shields (as I have at least 1 backup of each of my drives).

After erasing and setting up the drive again it showed again the usual speeds, around 850 MB/s write and 620 MB/s read speed. So far so good.

Then I cloned the erased content from another slow T7 Shield, what worked fine as the speed drop appears only when writing.

The weird thing then: After cloning the content suddenly the other "slow" drive also showed again normal speeds! But I also erased that drive, just to be "sure".

As I still have one set of "slow" T7 Shield drives I will do some more testing, maybe I can figure some more about this weird behavior.

Herbert
 
cleanton said:
Your T7 Shield is dying. Don't use it.
Click to expand...
Hmm, you are sure? Any hard facts that support this idea?

Just curious, as
- my T7 Shields are not old at all, means less than two years
- my drives are neither full (<50%) nor face hard usage
- my drives worked perfect until I upgraded from Ventura to Sequoia
- my standard T7 have the same age, are more used and do not show this behavior

Is there any possibility to check the "health" of these drives?

Herbert
 
herbert7265 said:
Hmm, you are sure? Any hard facts that support this idea?

Just curious, as
- my T7 Shields are not old at all, means less than two years: Mine was one year old
- my drives are neither full (<50%) nor face hard usage: Not necessary
- my drives worked perfect until I upgraded from Ventura to Sequoia: Coincidence
- my standard T7 have the same age, are more used and do not show this behavior

Is there any possibility to check the "health" of these drives?

Herbert
Click to expand...

"Any hard facts that support this idea?"

My experience. I lost 20 GB of data.
 
Fishrrman said:
See my replies #2 and #8 above...
Click to expand...
@Fishrrman

Thank you very much for your comment and the information provided.

Now, I am for sure not the specialist in all these topics, just a Mac user, but I still struggle with this topic, especially to believe that the drives are damaged, even dying.

As already mentioned in one of my former posts, I have a total of 4 Samsung T7 Shields, all with a capacity of 2 TB. I also have 3 Samsung T7, also with a capacity of 2 TB.

The standard Samsung T7 work normal at this moment.

As mentioned, on Monday I erased 2 of my T7 Shields and they came back to normal behavior and performance.

Today I started doing some more testing with my 2 remaining T7 Shields, which also show the slow performance.

1) I checked the performance of one of the drives with "Blackmagic Disk Speed Test" and "AJA Sytem Test Lite". Both tests showed the dramatically decreased write performance in the area of 6 MB/s!

2) Then I erased the drive with Disk Utility. An interesting observation in here, I already made it during my former tests, is the fact that erasing the disk took quite some time, around 2+ minutes.

3) Directly after erasing the drive I made another performance test and it showed "normal" performance values again, means write speeds around 830 MB/s and read speeds around 700 MB/s.

4) Then I checked the the drive with the Samsung Magician software. There was a firmware update available, which I installed without problems, an then I did also the Diagnostic Scan and Performance Benchmark with the Samsung software. Please see below the results.

1735150326050.png


1735150359462.png


1735150398660.png


1735150421493.png


1735150737036.png


1735150760612.png


5) At this moment I am copying the data back on the drive and then I will do some additional testing to see if anything changed.

6) If everything works out I will apply the same procedure (again) to all my T7 Shields.

My, very personal and still temporary, summary:
- Yes, something seems to be "off" with the Samsung T7 Shield drives, but I have still no idea what can be the real root cause for this. In my case I did not recognize anything before I went from Mac OS Ventura to Mac OS Sequoia, so that could be an aspect to be considered. Also, after erasing now already 3 drives all of them work again as before.

- Yes, maybe these drives have a problem, may even be "dying", but I still have my doubts in here. On the other side, I am not overly concerned about that as I have backups of these drives on other drive types.

So I will still do some testing to see if I can figure out what is going on in here.

Herbert
 
I'd like to add some additional observations to my replies 2 and 8 above.

I've discovered that "the problem" (slow write speeds) occurs whether the drive is formatted to HFS+ or APFS. Doesn't seem to matter.

Also...
I installed the "Samsung Magician" software and upgraded both of my t7 Shield drives to the latest firmware.

Result:
The problem is STILL THERE.
The firmware update made no difference.

If I connect my Crucial X9 SSD (also a USB3.1 gen2 1tb external SSD), read and write speeds are right-on-the-money, using the same test app (I've been using AJA System Test Lite)...
 
Fishrrman said:
I've discovered that "the problem" (slow write speeds) occurs whether the drive is formatted to HFS+ or APFS. Doesn't seem to matter.

Also...
I installed the "Samsung Magician" software and upgraded both of my t7 Shield drives to the latest firmware.

Result:
The problem is STILL THERE.
The firmware update made no difference.
Click to expand...
Have you (not sure if possible at all for you) also erased one of your drives and then checked again?

As described, my T7 Shields got back to normal speeds after (!) I erased the drive and re-configured them (APFS, GUID). My drives have originally been configured when my MacBook Pro was running Mac OS Ventura, I never used Sonoma, I now run Sequoia 15.2.

I upgraded the firmware of my drives after I erased and re-configured them.

What makes me doubt the theory that the drives are really the problem, at least that they seem to be "dying", are facts like
- all my 4 T7S drives (less than 2 years old, not hardly used) "fail" (show slow write speeds) exactly at the same moment
- all 4 drives come back to normal speeds after erasing and re-configuring them
- the slow speeds never showed up before I upgraded from Ventura to Sequoia

Herbert
 
"Have you (not sure if possible at all for you) also erased one of your drives and then checked again?"

I did this earlier (before the latest firmware upgrade).

Although it worked for a little while, the drives soon "reverted back" to their former behavior.
 
herbert7265 said:
As described, my T7 Shields got back to normal speeds after (!) I erased the drive and re-configured them (APFS, GUID). My drives have originally been configured when my MacBook Pro was running Mac OS Ventura, I never used Sonoma, I now run Sequoia 15.2.
Click to expand...
That slow write speeds fixing itself when erasing sounds a lot like what happens when TRIM isn't working (which it isn't aside from APFS' own garbage cleanup since macOS doesn't support support TRIM over USB) Windows does this automatically so the slowdowns don't happen there.

Since you said it was working fine in Sonoma, it almost sounds like even the APFS garbage collection isn't working correctly either.
 
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I had this problem a few years back in Ventura, (there was a thread somewhere) my only option was to wipe the OS fully clean and start again then restore from a backup.

Something is corrupted somewhere and you'll pull your hair out till you do this.

it was when they first released the security feature to allow or deny drives to connect to the mac that sent it slow.

Edit: link here: my old thread
 
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