Free space, but no uploads anymore

[Alexey]

the minimum is 5 GiB,
see

@littleskunk

We also need to increase the free space buffer from 500MB to 5GB. Because of the TTL nodes will switch between full and free space more frequently. Combined with an higher upload rate a 500MB buffer would give the customer a bad experience. The customer will get a decent number of failed uploads. By increasing the free space buffer we can make sure the storage node can accept 100MBit/s for 5 more minutes after passing the threshold. I am not saying that a customer would ever upload such an amount but technically the storage nodes are capable of handling it. So we can as well increase the free space buffer to make it possible for both sides.