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Starting a Validator

Configure Velas CLI​

The Velas cli includes get and set configuration commands to automatically set the --url argument for cli commands. For example:

velas config set --url https://explorer.testnet.velas.com/rpc

While this section demonstrates how to connect to the Devnet cluster, the steps are similar for the other Velas Clusters.

Confirm The Cluster Is Reachable​

Before attaching a validator node, sanity check that the cluster is accessible to your machine by fetching the transaction count:

velas transaction-count

Confirm your Installation​

Try running following command to join the gossip network and view all the other nodes in the cluster:

velas-gossip spy --entrypoint bootstrap.testnet.velas.com:8001
# Press ^C to exit

Enabling CUDA​

If your machine has a GPU with CUDA installed (Linux-only currently), include the --cuda argument to velas-validator.

When your validator is started look for the following log message to indicate that CUDA is enabled: "[<timestamp> solana::validator] CUDA is enabled"

System Tuning​

Linux​

Automatic​

The Velas repo includes a daemon to adjust system settings to optimize performance (namely by increasing the OS UDP buffer limits, and scheduling PoH with realtime policy).

The daemon (solana-sys-tuner) is included in the Velas binary release. Restart it, before restarting your validator, after each software upgrade to ensure that the latest recommended settings are applied.

To run it:

sudo solana-sys-tuner --user $(whoami) > sys-tuner.log 2>&1 &

Manual​

If you would prefer to manage system settings on your own, you may do so with the following commands.

Increase UDP buffers​
sudo bash -c "cat >/etc/sysctl.d/20-solana-udp-buffers.conf <<EOF
# Increase UDP buffer size
net.core.rmem_default = 134217728
net.core.rmem_max = 134217728
net.core.wmem_default = 134217728
net.core.wmem_max = 134217728
EOF"
sudo sysctl -p /etc/sysctl.d/20-solana-udp-buffers.conf
Increased memory mapped files limit​
sudo bash -c "cat >/etc/sysctl.d/20-solana-mmaps.conf <<EOF
# Increase memory mapped files limit
vm.max_map_count = 500000
EOF"
sudo sysctl -p /etc/sysctl.d/20-solana-mmaps.conf

Add

LimitNOFILE=500000

to the [Service] section of your systemd service file, if you use one, otherwise add it to /etc/systemd/system.conf.

sudo systemctl daemon-reload
sudo bash -c "cat >/etc/security/limits.d/90-solana-nofiles.conf <<EOF
# Increase process file descriptor count limit
* - nofile 500000
EOF"
### Close all open sessions (log out then, in again) ###

Generate identity​

Create an identity keypair for your validator by running:

velas-keygen new -o ~/validator-keypair.json

The identity public key can now be viewed by running:

velas-keygen pubkey ~/validator-keypair.json

Note: The "validator-keypair.json” file is also your (ed25519) private key.

Paper Wallet identity​

You can create a paper wallet for your identity file instead of writing the keypair file to disk with:

velas-keygen new --no-outfile

The corresponding identity public key can now be viewed by running:

velas-keygen pubkey ASK

and then entering your seed phrase.

See Paper Wallet Usage for more info.

Vanity Keypair​

You can generate a custom vanity keypair using solana-keygen. For instance:

velas-keygen grind --starts-with e1v1s

Depending on the string requested, it may take days to find a match...

Your validator identity keypair uniquely identifies your validator within the network. It is crucial to back-up this information.

If you don’t back up this information, you WILL NOT BE ABLE TO RECOVER YOUR VALIDATOR if you lose access to it. If this happens, YOU WILL LOSE YOUR ALLOCATION OF SOL TOO.

To back-up your validator identify keypair, back-up your "validator-keypair.json” file or your seed phrase to a secure location.

More Velas CLI Configuration​

Now that you have a keypair, set the velas configuration to use your validator keypair for all following commands:

velas config set --keypair ~/validator-keypair.json

You should see the following output:

Wallet Config Updated: /home/solana/.config/solana/wallet/config.yml
* url: http://explorer.testnet.velas.com/rpc
* keypair: /home/solana/validator-keypair.json

Airdrop & Check Validator Balance​

Airdrop yourself some VLX to get started:

velas airdrop 10 --url http://bootstrap.testnet.velas.com

Note that airdrops are only available on bootstrap node at Devnet.

To view your current balance:

velas balance

Or to see in finer detail:

velas balance --lamports

Create Vote Account​

If you haven’t already done so, create a vote-account keypair and create the vote account on the network. If you have completed this step, you should see the “vote-account-keypair.json” in your Velas runtime directory:

velas-keygen new -o ~/vote-account-keypair.json

The following command can be used to create your vote account on the blockchain with all the default options:

velas create-vote-account ~/vote-account-keypair.json ~/validator-keypair.json

Read more about creating and managing a vote account.

Trusted validators​

If you know and trust other validator nodes, you can specify this on the command line with the --trusted-validator <PUBKEY> argument to velas-validator. You can specify multiple ones by repeating the argument --trusted-validator <PUBKEY1> --trusted-validator <PUBKEY2>. This has two effects, one is when the validator is booting with --no-untrusted-rpc, it will only ask that set of trusted nodes for downloading genesis and snapshot data. Another is that in combination with the --halt-on-trusted-validator-hash-mismatch option, it will monitor the merkle root hash of the entire accounts state of other trusted nodes on gossip and if the hashes produce any mismatch, the validator will halt the node to prevent the validator from voting or processing potentially incorrect state values. At the moment, the slot that the validator publishes the hash on is tied to the snapshot interval. For the feature to be effective, all validators in the trusted set should be set to the same snapshot interval value or multiples of the same.

It is highly recommended you use these options to prevent malicious snapshot state download or account state divergence.

Connect Your Validator​

Connect to the cluster by running:

velas-validator \
  --identity ~/validator-keypair.json \
  --vote-account ~/vote-account-keypair.json \
  --ledger ~/validator-ledger \
  --rpc-port 8899 \
  --entrypoint bootstrap.testnet.velas.com:8001 \
  --limit-ledger-size \
  --log ~/velas-validator.log

Lastly, to configure log rotation, please run the following:

# Setup log rotation

cat > logrotate.sol <<EOF
~/velas-validator.log {
  rotate 7
  daily
  missingok
  postrotate
    systemctl kill -s USR1 sol.service
  endscript
}
EOF
sudo cp logrotate.sol /etc/logrotate.d/sol
systemctl restart logrotate.service

To force validator logging to the console add a --log - argument, otherwise the validator will automatically log to a file.

Note: You can use a paper wallet seed phrase for your --identity and/or --vote-account keypairs. To use these, pass the respective argument as velas-validator --identity ASK ... --vote-account ASK ... and you will be prompted to enter your seed phrases and optional passphrase.

Confirm your validator connected to the network by opening a new terminal and running:

velas-gossip spy --entrypoint bootstrap.testnet.velas.com:8001

If your validator is connected, its public key and IP address will appear in the list.

Controlling local network port allocation​

By default the validator will dynamically select available network ports in the 8000-10000 range, and may be overridden with --dynamic-port-range. For example, velas-validator --dynamic-port-range 11000-11010 ... will restrict the validator to ports 11000-11010.

Limiting ledger size to conserve disk space​

The --limit-ledger-size argument will instruct the validator to only retain the last couple hours of ledger. To retain the full ledger, simply remove that arg.

Systemd Unit​

Running the validator as a systemd unit is one easy way to manage running in the background.

Assuming you have a user called vel on your machine, create the file /etc/systemd/system/vel.service with the following:

[Unit]
Description=Velas Validator
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=always
RestartSec=1
User=vel
LimitNOFILE=1000000
LogRateLimitIntervalSec=0
Environment="PATH=/bin:/usr/bin:/home/vel/.local/share/velas/install/active_release/bin"
ExecStart=/home/vel/bin/validator.sh

[Install]
WantedBy=multi-user.target

Now create /home/vel/bin/validator.sh to include the desired velas-validator command-line. Ensure that the 'exec' command is used to start the validator process (i.e. "exec velas-validator ..."). This is important because without it, logrotate will end up killing the validator every time the logs are rotated.

Ensure that running /home/vel/bin/validator.sh manually starts the validator as expected. Don't forget to mark it executable with chmod +x /home/vel/bin/validator.sh

Start the service with:

$ sudo systemctl enable --now vel

Logging​

Log output tuning​

The messages that a validator emits to the log can be controlled by the RUST_LOG environment variable. Details can by found in the documentation for the env_logger Rust crate.

Note that if logging output is reduced, this may make it difficult to debug issues encountered later. Should support be sought from the team, any changes will need to be reverted and the issue reproduced before help can be provided.

Log rotation​

The validator log file, as specified by --log ~/velas-validator.log, can get very large over time and it's recommended that log rotation be configured.

The validator will re-open its when it receives the USR1 signal, which is the basic primitive that enables log rotation.

If the validator is being started by a wrapper shell script, it is important to launch the process with exec (exec velas-validator ...) when using logrotate. This will prevent the USR1 signal from being sent to the script's process instead of the validator's, which will kill them both.

Using logrotate​

An example setup for the logrotate, which assumes that the validator is running as a systemd service called vel.service and writes a log file at /home/vel/velas-validator.log:

# Setup log rotation

cat > logrotate.vel <<EOF
/home/vel/velas-validator.log {
  rotate 7
  daily
  missingok
  postrotate
    systemctl kill -s USR1 vel.service
  endscript
}
EOF
sudo cp logrotate.vel /etc/logrotate.d/vel
systemctl restart logrotate.service

As mentioned earlier, be sure that if you use logrotate, any script you create which starts the velas validator process uses "exec" to do so (example: "exec velas-validator ..."); otherwise, when logrotate sends its signal to the validator, the enclosing script will die and take the validator process with it.

Disable port checks to speed up restarts​

Once your validator is operating normally, you can reduce the time it takes to restart your validator by adding the --no-port-check flag to your velas-validator command-line.

Using a ramdisk with spill-over into swap for the accounts database to reduce SSD wear​

If your machine has plenty of RAM, a tmpfs ramdisk (tmpfs) may be used to hold the accounts database.

When using tmpfs it's essential to also configure swap on your machine as well to avoid running out of tmpfs space periodically.

A 300GB tmpfs partition is recommended, with an accompanying 250GB swap partition.

Example configuration:

  1. sudo mkdir /mnt/velas-accounts
  2. Add a 300GB tmpfs parition by adding a new line containing tmpfs /mnt/velas-accounts tmpfs rw,size=300G,user=vel 0 0 to /etc/fstab (assuming your validator is running under the user "vel"). CAREFUL: If you incorrectly edit /etc/fstab your machine may no longer boot
  3. Create at least 250GB of swap space
  • Choose a device to use in place of SWAPDEV for the remainder of these instructions. Ideally select a free disk partition of 250GB or greater on a fast disk. If one is not available, create a swap file with sudo dd if=/dev/zero of=/swapfile bs=1MiB count=250KiB, set its permissions with sudo chmod 0600 /swapfile and use /swapfile as SWAPDEV for the remainder of these instructions
  • Format the device for usage as swap with sudo mkswap SWAPDEV
  1. Add the swap file to /etc/fstab with a new line containing SWAPDEV swap swap defaults 0 0
  2. Enable swap with sudo swapon -a and mount the tmpfs with sudo mount /mnt/velas-accounts/
  3. Confirm swap is active with free -g and the tmpfs is mounted with mount

Now add the --accounts /mnt/velas-accounts argument to your velas-validator command-line arguments and restart the validator.

Account indexing​

As the number of populated accounts on the cluster grows, account-data RPC requests that scan the entire account set -- like getProgramAccounts and SPL-token-specific requests -- may perform poorly. If your validator needs to support any of these requests, you can use the --account-index parameter to activate one or more in-memory account indexes that significantly improve RPC performance by indexing accounts by the key field. Currently supports the following parameter values: