Is there anyone doing the same–employing a bunch of HDDs as temp drives and plotting in parallel on them, one plot on each HDD? I have many small SATA HDDs (~3TB) but only one 512GB SSD so I tried taking the HDDs as temp drive.
Actually with just one HDD the speed is pretty acceptable–around 10hrs, compared to 7hrs on NVME SSD. (i7 10700, 32GB RAM, -r 2, -b 4000).
But then comes the problem: when I try to add more plots in parallel (with or without 1-2hrs stagger, -r 2, -b 4000) on more HDDs, one on each, the speed decreases dramatically–about 16 hrs with 4, and ~20 with 6, the more the slower. Telling from the time spent on each step, every phase got slowed down. I tested the same on other platforms such as R5-3600, i5-10400, and symptoms are the same.
I really wonder where the bottleneck is–CPU has more threads than allocated by the plots, and CPU usage is only 20-40% most of the time; RAM is abundant; and I ran reading/writing benchmark on all the HDDs (even if 8 together) at the same time, and their speed is just the same as solo.
Is anyone aware of the reason behind this and how to mitigate that? Much appreciate!