Table of contents
Synchronize the blocks of the testnet
Synchronize the blocks of the Ropsten testnet
Synchronize RinkeyBy test network blocks
start node sync
Synchronize mainnet blocks
Geth is installed, now we can try to run it as follows. Execute the following command, geth will start synchronizing blocks and store them in the current directory. The --syncmode fast parameter here means that we will sync blocks in "fast" mode.
In this mode, we direct the download of each block header and block body , but do not verify all transactions until all blocks are synchronized before obtaining the state of a system. This saves a lot of time in transaction verification.
geth --datadir .--syncmode fastUsually, when synchronizing the Ethereum blockchain, the client downloads and verifies each block and each transaction at the beginning , that is, it can start from the genesis block.
There is no doubt that if we don't add --syncmode fast parameter, sync will take a long time and has high resource requirements (it will need more RAM, and if you don't have fast storage, it will take a long time) .
Some articles will write this parameter as --fast, this is the parameter writing method of the fast synchronization mode in the past, and it has been replaced by
--syncmode fast replaces
Synchronize the blocks of the testnet
Synchronize the blocks of the Ropsten testnet
geth --testnet --datadir .--syncmode fast--testnet This parameter will tell geth to start and connect to the latest test network, which is Ropsten. The number of blocks and transactions of the test network will be significantly less than that of the main network, so it will be faster. But even syncing the testnet in quick mode can take hours.
Synchronize RinkeyBy test network blocks
geth --Rinkeby --datadir .--syncmode fastBuild your own private chain
Create genesis.json
Because there are too many blocks in the public network and synchronization takes too long, we can quickly understand Geth in the future, and we can try to use it to build a private chain that only belongs to us
First, we need to create the "genesis" state of the network, which is written in a small JSON file (for example, we named it genesis.json):
chainId: chain id, try not to be consistent with public chain id and test chain id
difficulty: mining difficulty coefficient, 2000 is not too big
gasLimit: the upper limit requirement of gas in a block
alloc: Initial account information, including an address and object, indicating how much money is in the balance once the genesis block is created
balance: balance, the unit is wei
{
"config": {
"chainId": 15,
"homesteadBlock": 0,
"eip150Block": 0,
"eip155Block": 0,
"eip158Block": 0,
"byzantiumBlock": 0,
"constantinopleBlock": 0,
"petersburgBlock": 0,
"istanbulBlock": 0
},
"alloc": {
"0x1E17ECE93b3c72277E4B22a58B87934C9F654089":{"balance":"900000000000000000000"}},
"coinbase": "0x0000000000000000000000000000000000000000",
"difficulty": "0x200",
"extraData": "",
"gasLimit": "0x2fefd8",
"nonce": "0x0000000000000042",
"mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"timestamp": "0x00"
}init initialize gensis.json
To create a blockchain with it as the genesis block, we can use the following command:
Where path/to/custom/data/folder is the directory where you store
geth --datadir path/to/custom/data/folder init gensis.json 
init initial trial private chain success
geth --datadir ~/桌面/geth-project/myChain/ init ~/桌面/geth-project/myChain/genesis.json
Start private chain
Running geth in the current directory will start this private chain
Note that the networkid must be set to be consistent with the chainId in the genesis block configuration
geth --datadir path/to/custom/data/folder --networkid 15We can see that the node started normally:
geth --datadir ~/桌面/geth-project/myChain --networkid 15
In this way, we have started a private chain of our own