Poor I/O performance on Asus Z790-P D4

Quartz · 16 Dec 2022 at 23:04

I have two NVME drives: a WD Black SN750 and a Corsair MP400 and I am getting about 300 MB/s when transferring data between them - both ways - when I should be getting 10 times that, and 10 Gb/s on my LAN connection. The test dataset is 110 GB.

I've just upgraded to an i7-13700 in a Z790-P D4, transferred the drives, updated all drivers, updated the BIOS, and reactivated Windows. The NVME drives are in slots M2_1 and M2_2. I have a RTX 4090 in the x16 slot and an Intel X550 NIC in the bottom x4 slot. BIOS is up to date. There's a 1TB NVME cache drive on the NAS.

I'm seeing high CPU activity on core 8 of my 13700 but have not managed to isolate the process.

Tetras · 16 Dec 2022 at 23:29

How large are the drives? Is the SN750 a SE? You may be exceeding their write cache.

Quartz · 17 Dec 2022 at 00:40

The SN750 is 500 GB and the MP400 is 4 TB. I thought about the cache issue but I read on overclock3d.net that they had to write 750 GB to their MP400 before overwhelming the cache - not that it had 750 GB of cache but the cache worked well enough that it coped with 750 GB. As for the NAS, I managed a solid 500 MB/s (5 Gbps) running off a SATA SSD in a different PC.

Tetras · 17 Dec 2022 at 00:52

Quartz said:
The SN750 is 500 GB and the MP400 is 4 TB. I thought about the cache issue but I read on overclock3d.net that they had to write 750 GB to their MP400 before overwhelming the cache - not that it had 750 GB of cache but the cache worked well enough that it coped with 750 GB. As for the NAS, I managed a solid 500 MB/s (5 Gbps) running off a SATA SSD in a different PC.

From the couple reviews I looked at, it did seem like the MP400 is pretty good with large transfers, but < 300 MB/s is very typical of the cache being exhausted. I guess it is possible the drives aren't recovering for some reason? THG said it took half an hour:

"Within half an hour of idle time, the SSD recovered over half of its full SLC cache and could write at full speed, which is much faster than some SSDs, but slower than the MP510 and MP600."

Corsair Force MP400 M.2 NVMe SSD Review: Speedy, Spacious QLC

Infused with a high-performance Gen3 controller and cheap QLC flash, Corsair’s Force MP400 is a low-cost performer with up to 8TB of capacity.

www.tomshardware.com

If you use a smaller dataset, e.g. 10GB, do you still only get 300 MB/s?

Quartz · 17 Dec 2022 at 09:50

Tetras said:
If you use a smaller dataset, e.g. 10GB, do you still only get 300 MB/s?

No. I tried copying a 4 GB folder to my NAS and it quickly went to 400 MB/s but subsided to a steady 315 MB/s. Copying between drives seems odd. I tried copying a 20 GB dataset and speeds would gradually rise to about 500 GB/s but then fall back to very low speeds, down as low as 11 MB/s. It's a very distinctive saw-tooth pattern.