C-min-rate Protocol A

I’m trying to understand what happens when i set c-min-rate 0 for Protocol A DRBD Proxy.
When setting to 0 would that mean to the controller to not have any limits, and when setting to 1M for example, then i’m telling the controller to not fall below that speed.
The difference i see when using the 0 and 1M is that 0 it syncs really quick but 1M it has a variable speed not maintaining very well, can drop low to almost nothing.

Thanks