Level 1

16 points

Incredibly slow transfer speed using exFAT

Hello everyone, i'm on macOS Ventura 13.0.1 and my iMac 27" (2019) have thunderbolt two port up to 40Gb/s.

I have bought an external USB SSD from Samsung (T7 Shield 2TB NVMe) that is recognised by macOS itself as a 10Gb/s device.

I NEED it to be formatted in exFAT, cause i do have to access files from different OS (Windows and Android), so please don't advice to format it in APFS.

Anyway, i'm seeing an incredibly slow transfer speed con this SSD, like 20 or more times slower than it should be (around 50MB/s or less instead of the "up to" 1GB/s attended).

It's slower than a normal 5400rpm hard drive formatted in HFS+.

This is why i'm here asking your help.

Any advice would be really appreciated.

Thanks

iMac 27″, macOS 13.0

Posted on Dec 3, 2022 12:06 AM

Top-ranking reply

Matti Haveri

Level 6

19,706 points

Posted on Dec 3, 2022 1:37 AM

Some exFAT settings might not be optimal for the Mac. It seems 128 kB Allocation Unit Size should be used if exFAT is used on a Mac. So usually it is recommended to format the disk as exFAST on the Mac.

https://www.partitionwizard.com/partitionmagic/allocation-unit-size-exfat.html

That said, I have used exFAT formatted with Windows 10 default formatting options (just some USB flash drives, though). The only problem was that a 128 GB flash drive formatted as exFAT (GUID) on Big Sur was seen only AFAIR 100 MB on Windows 10 while exFAT (Master Boot Record) showed all capacity. I would have presumed that GUID should be preferred.

EtreCheck is safe and usually recommended to make extra guesswork and questions unnecessary.

When troubleshooting I usually reset SMC and PRAM. Or try another cable or port, no hubs.

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24 replies

Feb 21, 2023 8:34 AM in response to Labor_MJ

Yes, but the crux of the matter is, that Apples handling of ExFAT does not NEED to be that slow or even that buggy. That seems to be a recent feature on the Notebooks; at least until recently well known treat on iPads. "Nobody" uses iPhones in connection with media transfers; they're too abysmally slow.

How come, that Apple is (probably) the only digitally inclined company of any significance in the world, that cannot handle the most prevalent data exchange format in the world - ExFAT - in a safe and also speedy way? How come?

Regards

wirezen Author

Level 1

16 points

Dec 3, 2022 12:53 AM in response to Matti Haveri

I've never installed any of those.

Also, i had put this SSD under Spotlight Privacy panel, just to be sure no other process would have interfere.

Is this EtreCheck safe and reliable?

Thanks

wirezen Author

Level 1

16 points

Dec 3, 2022 1:47 AM in response to Matti Haveri

Unfortunately i've made all of those already without luck.

The SSD has been formatted under macOS and i've tried to reset PRAM and SMC several times.

Do Apple recognize this issue?

Labor_MJ

Level 1

16 points

Dec 21, 2022 12:48 AM in response to dawepr

i hoped macOS 13.1 could have fix it but nope, nothing has change.

unfortunately only Apple can release a fix but i'm not sure they recognise the issue at all.

drkprs

Level 1

8 points

Jan 15, 2023 10:13 PM in response to wirezen

I believe this is an Apple problem, not sure if when there will be a fix.

Just update Ventura 13.1, the problem remains.

Labor_MJ

Level 1

16 points

Jan 24, 2023 2:18 AM in response to drkprs

Did anyone test this issue with macOS 13.2?

Jan 31, 2023 2:06 PM in response to Labor_MJ

I can confirm that the issue is still the same on macOS 13.2. Using MacBook Air M2 and transfer speeds are shocking

Labor_MJ

Level 1

16 points

Feb 21, 2023 7:26 AM in response to JimmyCMPIT

The RPM mention was only a comparison that shows how bad is the transfer rate of and SSD formatted in exFAT.

Labor_MJ

Level 1

16 points

Feb 21, 2023 8:23 AM in response to Kurt Friis

It's pretty clear to me, OP mentioned a 5400rpm drive as a comparison to show how bad performance of an SSD drive can be using this file system.

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Incredibly slow transfer speed using exFAT