p.1 #1 · CFExpress 4.0 Type B real world file transfer rate
I have an OWC Atlas Ultra CFExpress type B 4.0 card and the OWC CFExpress 4.0 reader. I also have the Prodigital CFExpress 4.0 reader. When using these readers and the CFExpress 4.0 card, on a PC with a USB4 40Gbps port, I get real world file transfers from the card to the internal SSD on the PC of about 1800-2000 MBytes/Sec. About 1.8 - 2 Gigabytes per sec. As measured by Windows in the file transfer popup.
I think I should be getting more like 3000MBytes/sec or 3.0 GB/sec. Is there some reason I never really get more than about 2 GBytes per sec real world speed? It's very fast but not as fast as I would expect based on the spec. I have a MSI Meg Z790 ACE Max MB and an internal NVME SSD, (WD Black).
Is my motherboard somehow limiting the actual data rate I get? I seem to get slightly faster transfers from external TB4 SSDs but not too much faster, maybe 2000-2400 MBytes/sec.
Any ideas on if there is something wrong or maybe I should get a different card reader?
p.1 #2 · CFExpress 4.0 Type B real world file transfer rate
Try using Crystal Diskmark with a fairly long run length, like 64GB to determine read and write speeds of the card/reader alone. Generally write speed will slow down after a while and the manufacturers often list the max burst speeds.
Your internal SSD transfer target will also slow down after the static and dynamic SLC cache buffers are exhausted. It's common for QLC SSDs to reach a steady state of 500MB/sec. writes and lower grade TLC SSDs to reach a steady state of 1000MB/sec. The better TLC SSDs are more like 1.5-2.0 GB/sec. and some PCIe 5.0 are higher. If you need highest sustained writes some of the enterprise SSDs are more optimized for that. SSDs are so crazy expensive now it's not likely worth upgrading your internal SSDs. 4TB are often a sweet spot for performance for M.2 FF.
If you are transferring many TB per session day in and day out, then speed is more important and you pay for it. If only a smaller amount, then does a few minutes make a difference?
p.1 #3 · CFExpress 4.0 Type B real world file transfer rate
It makes no real big difference, 2000MB/Sec vs 3000. I am just wondering if I have something configured wrong or if I bought a slower card and/or card reader. I'm also curious what actual real world transfer rates other people are getting.
p.1 #4 · CFExpress 4.0 Type B real world file transfer rate
2000 MB/sec. is pretty good for large transfers. The read benchmarks will tell you if it is possible to improve on that. If so then which SSD model/capacity is your target and is it a single or maybe multiples striped?
I don't get more than 1000 but I'm using a laptop in the area with the species and downloading to 2-3 simultaneous targets. Weight is a critical issue in most countries so I'm not into SSDs over 80g (10g/TB) or those big, heavy readers.
There are better ways of copying rather than using Win native tools. A multi-threaded program helps sometimes depending on where the bottleneck is.
p.1 #5 · CFExpress 4.0 Type B real world file transfer rate
My target is a Western Digital Black SN850X Nvme drive. Just a single NVME. I also have a laptop that has a PCIE 5 drive as the boot C: drive, a Samsung 9100 Pro. I tried it on that laptop but it's about the same 1800-2000 MBytes/sec real world transfers. It's slightly slower than the desktop actually but in the same range.
There's a bottleneck somewhere in these systems I think but I don't know where. Practically speaking 1800-2000 MBytes/sec xfrs are fine but I just expected more.
