dirty_ratio & dirty_background_ratio settings with huge memory

Hi,
I've got cutomer with really huge RAM, now it's:
total used free shared buffers cached
Mem: 3102111 3052596 49515 208801 992 2961185
-/+ buffers/cache: 90418 3011693
Swap: 8191 1 8190

(free -m)

and before it was twice more (6TB).

and trying to figure out how to set dirty_ratio & dirty_background_ratio
parameters. Even for normal sized server those default sizes are to high,
but now would be ridiculously huge, respectively 1,24TB and 300GB.
I'm thinking about 1 percent for dirty_ratio and not using
dirty_background_ratio because it's not possible to set it below 1% but to
set dirty_background_bytes instead to about 1-2GB.
Maybe someone has got other experience with RAM of this size and those
settings?

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