Help with an External SSD

[ger19]

Hoping someone can help me with selecting an external ssd for the iMac. I already bought an enclosure that I believe is rated well and have it plugged into one of the thunderbolt drives. It says it will transfer at 10Gb/s.

https://www.amazon.com/dp/B09XV9XGHZ?psc=1&ref=ppx_yo2ov_dt_b_product_details

It has an enclosure to put an M.2 ssd in it and I bought this one.

Kingston NV2 1TB M.2 2280 NVMe Internal SSD | PCIe 4.0 Gen 4x4 | Up to 3500 MB/s | SNV2S/1000G

Kingston’s NV2 PCIe 4.0 NVMe SSD is a substantial next-gen storage solution powered by a Gen 4x4 NVMe controller. NV2 delivers lower power requirements and lower heat to help optimize your system’s performance and deliver value without sacrifice. The compact single-sided M.2 2280 (22x80mm) design...

www.amazon.com

I put it in and am getting very poor speed tests from the Black Magic Disk Speed Test. Write speed is 650MB/s and Read speed is 630MB/s. I think it's the drive I bought and am willing to buy another one but thought I'd get some opinions here on whether or not it is the drive that's the bottleneck and, if so, what would be a good drive to buy. I have some questions about heat of the faster drives, but lest discuss that once there's something to consider.

Thank you.

 

[Bigwaff]

I already bought an enclosure that I believe is rated well and have it plugged into one of the thunderbolt drives. It says it will transfer at 10Gb/s.

This hub is not a Thunderbolt hub but a USB hub. 10Gb/s is about 1250 MB/s... and you won't get those speeds in real world usage, especially w/ Apple Silicon machines. There are blog posts, articles, and forum posts lamenting the poor USB 3.1 Gen 2 performance when connected to TB ports. Here is one for example -

M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

It’s limited to 5 Gb/s, giving read rates of about 400 MB/s and writes at about 430 MB/s. Fine for Time Machine backups, but bad with NVMe drives.

eclecticlight.co

For this hub, looks like all devices attached will share the bandwidth. Remove all other attached devices and test the SSD drive again.

 

[chabig]

The declared USB port speed (10Gbps) is just a theoretical maximum number. In actual use, you should achieve about 2/3 of that. Your measured speed is right in the ballpark.

USB 3.2 Speed Comparison & Real-world Performance

Since the introduction of USB 3.0, making sense of USB marketing names has been a source of frustration for consumers. This is largely due […]

www.everythingusb.com

 

[Dc2006ster]

I recently purchased a 4TB Samsung T7 Shield that I connected to the Thunderbolt3/USB C Gen 2 port on my 2017 iMac 5K. I get around 850 - 900MB/s on Black magic.

 

[ger19]

Thank you. The speed isn't what I hoped for but this discussion kept me from going out and getting a new drive. It will be more than sufficient for my needs, but faster is always better. FWIW, those speeds are with nothing else connected to the enclosure. For me, the whole point of the enclosure was a way to hide a drive and not take away from the look of the iMac. It also didn't hurt that it raised the monitor up a bit.

 

[chabig]

Speed like you have was unheard of with rotating hard drives.

 

[Fishrrman]

I think the name "Kingston" may have something to do with it.
Crucial, Sandisk or Samsung might yield speeds a little higher, say, around 875-900MBps.

I just plugged in my Samsung t7 shield (USB3.1 gen2) into my 2018 Mini, and AJA System Test Lite shows read speeds of 924 and writes of 928. (of course the Mini is Intel-based)