SSD to SSD clone speeds slowly dropping to below 1GB/min

[Blackhawk441]

I'm using Clonezilla Live for the first time to try to clone my SATA SSD to my new NVMe SSD. The transfer will start out at a good clip (13+ GB/ min) but will steadily slow down to the point that with the Debian distro, which I left running overnight last night, was below 1 GB/min by the time I woke up on the morning while only 33% through my main partition.

System specs:
ASRock X670E Steel Legend mobo
7800X3D CPU
32GB DDR5
Source SSD: Samsung 870 EVO 2TB SATA (two months old, fresh-ish Windows install)
Destination SSD: Samsung 990 EVO 2TB m.2 NVMe connected @ PCIe 5x2 in CPU lane
Main partition: ~1.8 TB with 300GB free

I tried both the Debian distro and then the Ubuntu distro and both exhibited this slow, continuous transfer speed decrease. Debian went to sub-1GB/min while running overnight, I tried Ubuntu this morning and within 40 minutes it was at 2.5GB/min and steadily decreasing and I shut it off because I didn't have that long to spare my computer today.

I am running standard mode ToRAM with all beginner settings, whole disk to whole disk. I don't think, although can't be sure, that it isn't thermal throttling - a few albeit short benchmarks I did on the NVMe drive were showing acceptable (~3500 MB/s+) read and write speeds with temps not exceeding 75C. The drive is installed with the motherboard-included heat sink installed, and temps on the heatsink were not exceeding 35C measured with an IR thermometer during the clone operations. The SATA drive has been operating perfectly as expected for its young lifetime.

Does anyone have any idea what's going on here, and how I could fix it? I know that the non-DRAM NVMe drive I have will not have the best sustained data transfer rates, but under 3GB/min, let alone under 1GB/min, makes me think there is some kind of problem. I wouldn't think either thermal throttling or the cache running out would lead to progressive steady transfer rate decline over time - those both would stabilize quickly, I would think. In my run this morning I noted it went from an initial rate of 13GB/min to 2.8GB/min by 40 minutes in, to 2.6GB/min and dropping 10 minutes later.

Many thanks to anyone who can help, this is a great little utility, but whether due to my own misconfiguration or an unknown hardware issue I can't seem to get it to work.

I should also note both distros I used were the most recent stable releases, both drives are showing 100% on S.M.A.R.T. and I was able to format the new in Windows.

[Blackhawk441]

Update: I was able to clone the drive using Samsung Magician in Win 10 in just over an hour with sustained rates of 22 GB/min, constrained by the source drive. Thermal throttling at 70C may have been relevant during my first try, although for my second attempt I had case fans at 100% which was sufficient during the Magician clone, although based on experimentation this shouldn't have throttled it below ~12GB/min let alone 1GB/min. I no longer need assistance but this may be of interest to the developers, it seems there was some kind of bug with this hardware.

[Steven Shiau]

Thanks for sharing that.I believe a newer Linux kernel in Clonezilla live in the future might solve this issue.

Steven