I have a lot of old servers and plenty of space to store plots. So I thought: why not give it a shot?
I want to share some interesting experience for those, who think buying super-fast SSDs will help. I think it won’t.
Here is my setup:
My desktop PCs are all AMD FX-8350 (8C, 8T) 3,5 Ghz. 32-64GB Ram.
My servers are all AMD Opteron 6380 (16C, 16T) 2.6 Ghz. 64-128GB Ram.
First test:
Desktop:Plotting: 2 Plots, 4 Cores per Plot, 8 GB RAM each, Temp-Drive is an SSD with 1TB. Both are using this drive, connected SATA3 (6GB/s). Time to finish for both plots: 10h.
Second test:
Server-Plotting: 2 Plots , 4 Cores per Plot, 8 GB each, Temp-Drive is an SSD with 1TB. Both are using this drive, connected SATA2 (3GB/s). Time to finish for both plots: 13h.
Why is the server PC slower? CPU-Speed or the slow SATA-Interface? Let’s find out:
Server-Plotting: 2 Plots parallel, 4 Cores per Plot, 8 GB RAM each, two separate 1 TB SSDs connected by a SATA3-Controller (PCIe x4). Time to finish for both plots: 13h.
So, SSDs speed or interface it NOT a bottleneck! A single SSD connected via SATA2 gives the same speed as two separate SSDs connected via SATA3.
And here is where it get’s really interesting. Let’s create 4 plots at once:
Server PC, 4 Plots parallel, 4 Cores per Plot, 8 GB RAM each, 4 separate 1 TB SSDs connected to an SATA3-Controller (PCIe x4). Time to finish for all four plots: 26h.
That’s what really surprises me. CPU cores do not matter, too. I tried everything, but I cannot utilize all the cores. I can create just 2 plots at once, no matter how many cores the CPU has, how much RAM is available or how fast the SSDs are. The third plot always increases the time by 50%, the fourth plot by 100% and so on… I think the real limitation of plotting is the memory interface/bandwidth.
What do you think?