Private Network on restart balance and transaction is gone?

I am running a private ethereum node with a single node.
and it creates a folder for the keystore and chaindata But on restart, all the data is gone even the balance as well.

init genesis.json is occurred only once and later only this:

geth –gcmode archive –port 3000 –networkid 15 –nodiscover –datadir=./block-data –maxpeers=2 –rpc –rpcaddr 0.0.0.0 –rpcport 8545 –rpccorsdomain “*” –rpcapi “eth,net,web3,personal,miner” –allow-insecure-unlock