# Running BLAST Mainnet from Source
[**Please follow these steps first if you have not done so already.**](https://docs.blastblockchain.com/developer-docs/blast-node-operators/building-a-node-from-source)
#### [#](https://community.optimism.io/docs/developers/nodes/mainnet/#get-the-data-directory)Get the data directory
The next step is to download the data directory for `op-geth`. You will need 500+ GB for this part alone.
1. Download the data directory snapshot. This is a large file so expect it to take some time. Bedrock Data Directory (XXGB)(opens new window)
2. Check the validity of your download. This is an important step. Corrupted data directories will make your node fail. So ensure your checksum matches.
```
sha256sum mainnet-bedrock.tar.zst
# expected output
ec4baf47e309a14ffbd586dc85376833de640c0f2a8d7355cb8a9e64c38bfcd1 mainnet-bedrock.tar.zst
```
OR
```
sha512sum mainnet-bedrock.tar.zst
# expected output
c17067b7bc39a6daa14f71d448c6fa0477834c3e68a25e96f26fe849c12a09bffe510e96f7eacdef19e93e3167d15250f807d252dd6f6f9053d0e4457c73d5fb mainnet-bedrock.tar.zst
```
3. Create the data directory in `op-geth` and fill it. This will take time.
Navigate into your `op-geth` directory and run these commands:
```
mkdir datadir
cd datadir
tar xvf <>
```
#### [#](https://community.optimism.io/docs/developers/nodes/mainnet/#create-a-shared-secret-between-op-geth-and-op-node)Create a shared secret between `op-geth` and `op-node`
1. Navigate into your `op-geth` directory and run these commands:
```
openssl rand -hex 32 > jwt.txt
cp jwt.txt ../optimism/op-node
```
#### [#](https://community.optimism.io/docs/developers/nodes/mainnet/#scripts-to-start-the-different-components)Scripts to start the different components
In the root of your working directory create a new directory: `scripts`.
#### [#](https://community.optimism.io/docs/developers/nodes/mainnet/#op-geth)`op-geth`
1. Navigate into your `scripts` directory:
2. Create a new file:
```
touch run-op-geth.sh
```
3. Make it executable:
```
chmod +x run-op-geth.sh
```
4. Insert this snippet of code into `run-op-geth.sh` and modify the path to the `op-geth` directory.
```
#! /usr/bin/bash
SEQUENCER_URL=https://mainnet-sequencer.blastblockchain.com/
cd <>
./build/bin/geth \
--datadir=./datadir \
--http \
--http.port=8545 \
--http.addr=0.0.0.0 \
--authrpc.addr=localhost \
--authrpc.jwtsecret=./jwt.txt \
--verbosity=3 \
--rollup.sequencerhttp=$SEQUENCER_URL \
--nodiscover \
--syncmode=full \
--maxpeers=0
```
Archive Nodes
You will also need to add `--gcmode archive`.
1. Run the following command to start `op-geth`:
```
./run-op-geth.sh
```
#### [#](https://community.optimism.io/docs/developers/nodes/mainnet/#op-node)`bl-node`
1. Navigate to the `scripts` directory you created.
2. Create a new file:
```
touch run-op-node.sh
```
3. Make it executable:
```
chmod +x run-op-node.sh
```
4. Insert this snippet of code into `run-bl-node.sh`:
```
#!/usr/bin/bash
L1URL=<< L1 RPC URL >>
L1KIND=basic
NET=mainnet
cd <>
./bin/op-node \
--l1=$L1URL \
--l1.rpckind=$L1KIND \
--l2=ws://localhost:8551 \
--l2.jwt-secret=./jwt.txt \
--network=$NET \
--rpc.addr=0.0.0.0 \
--rpc.port=8547
```
* Change `<< L1 RPC URL >>` to your local L1 node or a service provider's URL for the L1 node (L1 Ethereum). E.g. for Infura, `https://mainnet.infura.io/v3/API_KEY`.
* Set `L1KIND` to the network provider you are using (options: alchemy, quicknode, infura, parity, nethermind, debug\_geth, erigon, basic, any).
5. Run the following command to start `bl-node`:
```
./run-op-node.sh
```
#### [#](https://community.optimism.io/docs/developers/nodes/mainnet/#the-initial-synchronization)The initial synchronization
The datadir provided by Blast is not updated continuously, so before you can use the node you need a to synchronize it.
During that process you get log messages from `bl-node`, and nothing else appears to happen.
```
INFO [06-26|13:31:20.389] Advancing bq origin origin=17171d..1bc69b:8300332 originBehind=false
```
That is normal - it means that `bl-node` is looking for a location in the batch queue. After a few minutes it finds it, and then it can start synchronizing.
While it is synchronizing, you can expect log messages such as these from `bl-node`:
```
INFO [06-26|14:00:59.460] Sync progress reason="processed safe block derived from L1" l2_finalized=ef93e6..e0f367:4067805 l2_safe=7fe3f6..900127:4068014 l2_unsafe=7fe3f6..900127:4068014 l2_time=1,673,564,096 l1_derived=6079cd..be4231:8301091
INFO [06-26|14:00:59.460] Found next batch epoch=8e8a03..11a6de:8301087 batch_epoch=8301087 batch_timestamp=1,673,564,098
INFO [06-26|14:00:59.461] generated attributes in payload queue txs=1 timestamp=1,673,564,098
INFO [06-26|14:00:59.463] inserted block hash=e80dc4..72a759 number=4,068,015 state_root=660ced..043025 timestamp=1,673,564,098 parent=7fe3f6..900127 prev_randao=78e43d..36f07a fee_recipient=0x4200000000000000000000000000000000000011 txs=1 update_safe=true
```
And log messages such as these from `op-geth`:
```
INFO [06-26|14:02:12.974] Imported new potential chain segment number=4,068,194 hash=a334a0..609a83 blocks=1 txs=1 mgas=0.000 elapsed=1.482ms mgasps=0.000 age=5mo2w20h dirty=2.31MiB
INFO [06-26|14:02:12.976] Chain head was updated number=4,068,194 hash=a334a0..609a83 root=e80f5e..dd06f9 elapsed="188.373µs" age=5mo2w20h
INFO [06-26|14:02:12.982] Starting work on payload id=0x5542117d680dbd4e
```
[**#**](https://community.optimism.io/docs/developers/nodes/mainnet/#how-long-will-the-synchronization-take)**How long will the synchronization take?**
To estimate how long the synchronization will take, you need to first find out how many blocks you synchronize in a minute. You can use this [Foundry (opens new window)](https://book.getfoundry.sh/)script to get an estimated sync time.
1. Navigate to your `scripts` directory
2. Create a new file:
```
touch run-estimate.sh
```
3. Make it executable:
```
chmod +x run-estimate.sh
```
4. Insert this snippet of code into `run-estimate.sh`:
```
#!/usr/bin/bash
export ETH_RPC_URL=http://localhost:8545
CHAIN_ID=`cast chain-id`
echo Chain ID: $CHAIN_ID
echo Please wait
if [ $CHAIN_ID -eq 238]; then
L2_URL=https://rpc.blastblockchain.com
fi
if [ $CHAIN_ID -eq 239]; then
L2_URL=https://testnet-rpc.blastblockchain.com
fi
T0=`cast block-number --rpc-url $ETH_RPC_URL` ; sleep 60 ; T1=`cast block-number --rpc-url $ETH_RPC_URL`
PER_MIN=`expr $T1 - $T0`
echo Blocks per minute: $PER_MIN
if [ $PER_MIN -eq 0 ]; then
echo Not synching
exit;
fi
# During that minute the head of the chain progressed by thirty blocks
PROGRESS_PER_MIN=`expr $PER_MIN - 30`
echo Progress per minute: $PROGRESS_PER_MIN
# How many more blocks do we need?
HEAD=`cast block-number --rpc-url $L2_URL`
BEHIND=`expr $HEAD - $T1`
MINUTES=`expr $BEHIND / $PROGRESS_PER_MIN`
HOURS=`expr $MINUTES / 60`
echo Hours until sync completed: $HOURS
if [ $HOURS -gt 24 ] ; then
DAYS=`expr $HOURS / 24`
echo Days until sync complete: $DAYS
fi
```
5. Run the following command to get an estimate:
```
./run-estimate.sh
```
#### [#](https://community.optimism.io/docs/developers/nodes/mainnet/#operations)Operations
It is best to start `op-geth` first and shut it down last.