This may happen if you are using a machine with low RAM. As the difficulty for the block 0 maybe set to a high number. You can try the below points to decrease the difficulty and then start the private network.
P.S. The below points will drastically increase you block mining speed.
There are 2 ways to do this:
- Change the value of difficulty parameter in
genesis.json file to a small number(preferably set it to 0). You can refer to this example genesis file
"difficulty": "0x0", //difficulty set to zero in hexadecimal format
Problem with this method is that when the block number increases, the difficulty also starts increasing at a high rate. So, to tackle that problem refer to the below part.
- Try creating your own version of ethereum(takes about few minutes)
You can reduce the rate of block difficulty increament by making some changes in the consensus code of go-ethereum.
consensus.go which resides at
consensus/ethash/consensus.go and search for the below line.
return CalcDifficulty(chain.Config(), time, parent)
Now replace the above line with the below one.
Now build the go-ethereum using
make geth command.
I strongly recommend you to go through this article for much detailed implementation of the above process.