Howard’s original post doesn’t mention it (though Simon’s does), but if you are after maximizing the speed, the version of PCI (and therefor number of PCI lanes) that the enclosure supports is critical. It’s sometimes hard to confirm as the spec is sometimes hidden, but worth checking if you’re paying for a faster storage drive.
For reference, I have been using two different NVMe enclosures for several years:
- Tekc Cube (no longer avail) with a WD Black SN750 1TB
- Acacis 40Gbps with a WD Black SN850 2TB
When I got the Cube in 2020, it was the only empty enclosure I could find that supported TB3 make use of the faster NVMe drives (uses DSL6xxx/JHL6xxx Alpine Ridge). I’m still using it for the original purpose: with a 2019 iMac 27" that has a 2TB Fusion Drive inside. I have the external as the primary boot device, and the difference was unsurprisingly incredible. Tangent to the CCC thread, I have the external “cloning” on-system files to the internal Fusion Drive for one backup.
At the time I also looked at the OWC Express 4M2, which is an external enclosure that can take up to 4 NMVe drives and offered comparable speeds (+2000 MB/s). I was leaning that way and going to start with just one drive, when I noticed the following in the footnotes:
- Maximum single drive performance is 817 MB/s Reads and 711MB/s Writes due to the bandwidth of the 1X PCIe3.0 bus.
The OWC Express only achieves its throughput by r/w across multiple devices. That’s the difference the controller/PCI version can make.
And OWC had pre-announced the Envoy Express but listed it as throughput up to ~1500 Mbps. An email to their customer service back in 2020 confirmed it was a 2 lane controller.
The Thunderbolt 3 controller in this enclosure uses only two PCIe 3.0 lanes, so the maximum speed is limited to around that number.
Even today, the product page lists the ~1500 throughput in the bullets, but in the specs is the following, which I can see leading to a lot of confusion:
- (1) Host Port - Thunderbolt 3 (USB-C) up to 40 Gb/s (5000 MB/s)
Should be noted they have a faster Express Envoy 1M2 enclosure listed for preorder these days.
Just a few weeks ago I ran into this again. I’ve had my eye on a TB4 dock, I’ve been tempted by the CalDig TB4, but the “hub” built into my Dell U3223QE has worked well enough most of the time. I was excited to see the new SonnetTech dock has a built in NMVe slot, which would remove the occasional problem of not having an open port on my MBPro. While they don’t specify what controller or number of lanes, the 800 MB/s limit is a giveaway. And even their “SSD Compatibility” PDF adds confusing by listing the speeds of the drives, not what their enclosure can achieve.
Not surprising, you can see how quickly the current “best” changes, and even how hard it is to tell how an external drive will perform. TB4 or USB4 is the connection type and max throughput, but is only one piece of the puzzle.
FWIW, The newer Acacis (purchased in 2022) is attached to my M1 MBPro in a similar setup to the iMac, but without being the default boot device. macOS installed on both, CCC copying personal files between for backup and easy recovery. (Per other thread, I miss cloned backups too).