That copy speed difference is interesting.
The Pi 5 PCIe has one lane instead of 4 and other differences that make published SSD speeds useless. SSDs read speeds are almost always faster than what the Pi can handle while write speeds are mostly way slower than the published speeds and may drop to slower than PCIe gen 2 with heavy writes.
Apparently a commonly used Phison controller chip fails with the Pi 1 lane PCIe. There may be others with slow down problems with other controllers. After I get my NVMe board, I will test with several brands before deciding on gen 2 or 3. I often rip off the SSD label to identify the controller chip.
I am also going to benchmark the SSDs against their PCIe gen 3 in full 4 lane motherboards to see if the slow down is proportional, indicating a good controller in the SSD, or disproportional due to a poor controller.
If the disk does run faster, a process may then crash into a CPU to slow or push stuff into memory faster with an increase in paging, creating another slow down. I will test with 8 GB to make sure paging does not happen.
The Pi 5 PCIe has one lane instead of 4 and other differences that make published SSD speeds useless. SSDs read speeds are almost always faster than what the Pi can handle while write speeds are mostly way slower than the published speeds and may drop to slower than PCIe gen 2 with heavy writes.
Apparently a commonly used Phison controller chip fails with the Pi 1 lane PCIe. There may be others with slow down problems with other controllers. After I get my NVMe board, I will test with several brands before deciding on gen 2 or 3. I often rip off the SSD label to identify the controller chip.
I am also going to benchmark the SSDs against their PCIe gen 3 in full 4 lane motherboards to see if the slow down is proportional, indicating a good controller in the SSD, or disproportional due to a poor controller.
If the disk does run faster, a process may then crash into a CPU to slow or push stuff into memory faster with an increase in paging, creating another slow down. I will test with 8 GB to make sure paging does not happen.
Statistics: Posted by peterlite — Thu Feb 29, 2024 12:06 am