Many thanks for explanation.
I am generating plot with these parameters:
Machine is 4 x R9 280X (but only 2 are generating, no need for more because of HDD speed) + 8Gb ram.
devices.txt is :
0 0 8192 128 8192
0 1 8192 128 8192
command line parameters are:
gpuplotgenerator.exe generate "D:\plots" 30xxxxxxxxxxxxxxx778 10101000000000 2048000 8192
gpuplotgenerator.exe generate "D:\plots" 30xxxxxxxxxxxxxxx778 10101025000000 2048000 8192
gpuplotgenerator.exe generate "D:\plots" 30xxxxxxxxxxxxxxx778 10101050000000 2048000 8192
gpuplotgenerator.exe generate "D:\plots" 30xxxxxxxxxxxxxxx778 10101075000000 2048000 8192
gpuplotgenerator.exe generate "D:\plots" 30xxxxxxxxxxxxxxx778 10101100000000 2048000 8192
gpuplotgenerator.exe generate "D:\plots" 30xxxxxxxxxxxxxxx778 10101125000000 2048000 8192
gpuplotgenerator.exe generate "D:\plots" 30xxxxxxxxxxxxxxx778 10101150000000 2048000 8192
gpuplotgenerator.exe generate "D:\plots" 30xxxxxxxxxxxxxxx778 10101175000000 2048000 8192
It is 4Tb total per disk (range change for every hdd).
GpuPlotGenerator says:
-------------------------
GPU plot generator v3.0.0
-------------------------
Author: Cryo
Bitcoin: 138gMBhCrNkbaiTCmUhP9HLU9xwn5QKZgD
Burst: BURST-YA29-QCEW-QXC3-BKXDL
----
Checking input parameters...
----
Path: D:\plots
Nonces: 10101050000000 to 10101052047999 (500GB 0MB)
CPU memory: 2GB 0MB
----
Initializing OpenCL devices...
GPU[0] memory: 2GB 0MB
GPU[1] memory: 2GB 0MB
----
Creating CPU stagger buffer...
Creating CPU plots buffer...
Opening output file...
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Dedicated mining machine will be 8 or 16 Gb ram, 8 hdd (32Tb total).
Is there something I should change before plotting all drives, considering equipment and ram size?
That would be it, final step before mining, after this I should only wait to be done and start mining.
Will not bother more

It all seems good to me.
Maybe you can use a higher stagger size like 16384 as you have 8GB of memory for plotting. It'll reduce disk stress later for the mining process.