So, you’ve got a new M1 Mac, and a nice fast NMVe in an external Thunderbolt 4 enclosure, and you’re only getting 640MB\/s write speed? WAAAAAY TOOOO SLOOOOOW!!!<\/p>\n
That was the issue that just took me three days and $220 to resolve.<\/p>\n
(Turns out I didn’t need to spend the $220, either…)<\/p>\n
The issue:<\/p>\n
I put a 1TB NMVe drive into a Sabrent Thunderbolt enclosure, with the intent of using it with my M1 MacBook Air laptop (and soon to be Mac Studio.)<\/p>\n
I ran Sensei on it to check to the speed, and it was -terrible- : 640 MBs write. (The read was a more reasonable 1300.)<\/p>\n
I went through every test I could think of, including using a different drive; pluggin it into the other TB port; plugging it into the Caldigit TS3 hub; plugging it into my M1 MacMini. All the write speeds were pretty much the same: half the speed it should be.<\/p>\n
OK…. sigh… Must be that it’s a well-used drive, which I pulled from my main machine about a year ago.<\/p>\n
So, I hop on Amazon and buy two new WD 1tb drives, for $220. (I’m still waiting for them, but read on…)<\/p>\n
Again, using Sensei (highly recommended, BTW – shows more useful info than anything else I’ve used) I see that the drive report shows:<\/p>\n
80% life remaining
Data read: 98TB
data write: 75TB
read commands: 6.5 billion
write commands 1.6B
Hours 11,800<\/p>\n
(the really high numbers are because this was the boot drive, with Apple incessant writing to it)<\/p>\n
OK: that’s a lot… so I pulled another 1tb drive with these specs:<\/p>\n
100% life remaining
Data read: 3.3TB
data write: 760 MB
read commands: 44 Million
write commands 8 Million
Hours 15,000<\/p>\n
(More time in use, but about 1\/10th the wear and tear.)<\/p>\n
and threw it into the enclosure.<\/p>\n
Exact same results! Grrrr…<\/p>\n
I call Sabrent, thinking at this point, it had to be the enclosure. Tech support was great, and we tried all kinds of things, ending up with doing a secure(!) erase (which took 4 hours) and reformat. That bumped the speed up to 720.<\/p>\n
So, by now I’ve run the tests on two different M1 machines, with two different NMVe drives in the enclosure, with 100% consistent results.<\/p>\n
Then, 30 minutes ago, and by pure happenstance, I ran the test with my Caldigit hub in one port and the enclosure in the other mac port…<\/p>\n
… and got nearly 1200 for my write speed!<\/p>\n
WT..???<\/p>\n
Turns out that the TB ports respond weirdly: I found this on the OWC website…<\/p>\n
“the M1 CPU only supports one video output signal to its TB4 ports. When a Thunderbolt display is connected to an M1 Mac\u2019s TB4 port, the other Thunderbolt 4 port on the Mac does not need to support video output. It can then deliver the full PCIe data bandwidth potential to an attached external drive. “<\/p>\n
Get Up to 67% Faster External Drive Performance With Your M1 Mac!<\/a><\/p><\/blockquote>\n