What is Staking?
Staking is the process of locking up tokens to support a network while receiving a reward in return (rewards can be increased network utility, monetary compensation, etc.). The concept of staking was first formally introduced by Sunny King and Scott Nadal of Peercoin.
How Does Proof-of-stake Work?
To resist sybil attacks, a decentralized network must require that network influence is paid with a scarce resource. This makes it infeasibly expensive for an attacker to gain enough influence over the network to compromise its security. In proof-of-work systems, the scarce resource is computing power. On Metal Blockchain, the scarce resource is the native token, METAL. For a node to validate a blockchain on Metal Blockchain, it must stake METAL.
Staking Parameters on Metal Blockchain
When a validator is done validating the Primary Network, it receives back the METAL tokens it staked. It may receive a reward for helping to secure the network. A validator only receives a validation reward if it is sufficiently responsive and correct during the time it validates. Read the Metal Blockchain Litepaper to learn more about METAL and the mechanics of staking.
Staking rewards are sent to your wallet address at the end of the staking term as long as all of these parameters are met.
- The minimum amount that a validator must stake is 2,000 METAL
- The minimum amount that a delegator must delegate is 25 METAL
- The minimum amount of time one can stake funds for validation is 2 weeks
- The maximum amount of time one can stake funds for validation is 1 year
- The minimum amount of time one can stake funds for delegation is 2 weeks
- The maximum amount of time one can stake funds for delegation is 1 year
- The minimum delegation fee rate is 2%
- The maximum weight of a validator (their own stake + stake delegated to them) is the minimum of 3 million METAL and 5 times the amount the validator staked. For example, if you staked 2,000 METAL to become a validator, only 8000 METAL can be delegated to your node total (not per delegator)
A validator will receive a staking reward if they are online and response for more than 80% of their validation period, as measured by a majority of validators, weighted by stake. You should aim for your validator be online and responsive 100% of the time.
You can call API method
info.uptime on your node to learn its weighted uptime and what percentage of the network currently thinks your node has an uptime high enough to receive a staking reward. See here.
You can get another opinion on your node's uptime from the Validators tab on the Metal Blockchain Explorer's Subnets page.
If your reported uptime is not close to 100%, there may be something wrong with your node setup, which may jeopardize your staking reward.
If this is the case, please see here.
Note that only checking the uptime of your validator as measured by non-staking nodes, validators with small stake, or validators that have not been online for the full duration of your validation period can provide an inaccurate view of your node's true uptime.
Validators secure Metal Blockchain, create new blocks/vertices, and process transactions. To achieve consensus, validators repeatedly sample each other. The probability that a given validator is sampled is proportional to its stake.
When you add a node to the validator set, you specify:
- Your node’s ID
- When you want to start and stop validating
- How many METAL you are staking
- The address to send any rewards to
- Your delegation fee rate (see below)
The minimum amount that a validator must stake is 2,000 METAL.
Note that once you issue the transaction to add a node as a validator, there is no way to change the parameters. You can’t remove your stake early or change the stake amount, node ID, or reward address. Please make sure you’re using the correct values in the API calls below. If you want to add more tokens to your own validator, you can delegate the tokens to this node - but you cannot increase the base validation amount (so delegating to yourself goes against your delegation cap).
Running a Validator
If you’re running a validator, it’s important that your node is well connected to ensure that you receive a reward. See here.
When you issue the transaction to add a validator, the staked tokens and transaction fee are deducted from the addresses you control. When you are done validating, the staked funds are returned to the addresses they came from. If you earned a reward, it is sent to the address you specified when you added yourself as a validator.
Allow API calls
To make API calls to your node from remote machines, allow traffic on the API port (
9650 by default), and run your node with argument
You should disable all APIs you will not use via command-line arguments. You should configure your network to only allow access to the API port from trusted machines (e.g., your personal computer.)
Why Is My Uptime Low?
Every validator on Metal Blockchain keeps track of the uptime of other validators. Every validator has a weight (i.e. the amount staked on it.) The more weight a validator has, the more influence they have when validators vote on whether your node should receive a staking reward. You can call API method
info.uptime on your node to learn its weighted uptime and what percentage of the network stake currently thinks your node has an uptime high enough to receive a staking reward.
You can also see the connections a node has by calling
info.peers, as well as the uptime of each connection. This is only one node’s point of view. Other nodes may perceive the uptime of your node differently. Just because one node perceives your uptime as being low does not mean that you will not receive staking rewards.
If your node's uptime is low, make sure you're setting config option
--public-ip=[NODE'S PUBLIC IP] and that your node can receive incoming TCP traffic on port 9651.
The only secret that you need on your validating node is its Staking Key, the TLS key that determines your node’s ID. The first time you start a node, the Staking Key is created and put in
$HOME/.metalgo/staking/staker.key. You should back up this file (and
staker.crt) somewhere secure. Losing your Staking Key could jeopardize your validation reward, as your node will have a new ID.
You do not need to have METAL funds on your validating node. In fact, it's best practice to not have a lot of funds on your node. Almost all of your funds should be in "cold" addresses whose private key is not on any computer.
Follow this tutorial to learn how to monitor your node's uptime, general health, etc.
Validating In Tahoe
Validating in Tahoe requires just
1 METAL. So you can easily set up your validator node and learn more about validating.
A delegator is a token holder, who wants to participate in staking, but chooses to trust an existing validating node through delegation.
When you delegate stake to a validator, you specify:
- The ID of the node you’re delegating to
- When you want to start/stop delegating stake (must be while the validator is validating)
- How many METAL you are staking
- The address to send any rewards to
The minimum amount that a delegator must delegate is 25 METAL.
Note that once you issue the transaction to add your stake to a delegator, there is no way to change the parameters. You can’t remove your stake early or change the stake amount, node ID, or reward address.
If the validator that you delegate tokens to is sufficiently correct and responsive, you will receive a reward when you are done delegating. Delegators are rewarded according to the same function as validators. However, the validator that you delegate to keeps a portion of your reward–specified by the validator’s delegation fee rate.
When you issue the transaction to delegate tokens, the staked tokens and transaction fee are deducted from the addresses you control. When you are done delegating, the staked tokens are returned to your address. If you earned a reward, it is sent to the address you specified when you delegated tokens.
Is There a Tool to Check if a Validator is up and running?
Yes, enter your node ID here.
How Is It Determined Whether a Validator Receives a Staking Reward?
When a node leaves the validator set, the validators vote on whether the leaving node should receive a staking reward or not. If a validator calculates that the leaving node was responsive for more than the required uptime (currently 80%), the validator will vote for the leaving node to receive a staking reward. Otherwise, the validator will vote that the leaving node should not receive a staking reward. The result of this vote, which is weighted by stake, determines whether the leaving node receives a reward or not.
Each validator only votes "yes" or "no". It does not share its data such as the leaving node's uptime.
Each validation period is considered separately. That is, suppose a node joins the validator set, and then leaves. Then it joins and leaves again. The node's uptime during its first period in the validator set does not affect the uptime calculation in the second period, hence, has no impact on whether the node receives a staking reward for its second period in the validator set.