# V22.0¶

Node Protocol Database Release Date Release Notes GitHub Links
22.0 18 21 2021-05-14 V22.0 Release - Milestone - Changelog
Known issue with RocksDB: RPC unchecked_keys not working properly

Issue: The RPC unchecked_keys is returning 0 for all calls when used with the RocksDB backend. This known issue will be resolved in a future release.

Solution: Until the issue is resolved any integrations using this command should remain on the existing LMDB backend

### Database upgrades with increased disk requirements¶

Upgrade requires 150GB of free disk space

This version performs a database upgrade of the ledger format on disk. This process requires a large amount of disk space and due to the DoS attack on nano earlier in the year, the disk space requirements during upgrade require attention.

Upgrading to V22.0 requires approximately 150GB of free disk space, however, the final upgraded ledger size is ~50GB. The upgrade takes between 30 minutes and 4 hours on most machines, depending on the speed of the disk.

Due to these impacts, upgrading the database in a staging environment is recommended where possible. For operators who are unable to perform this direct upgrade, you may download a snapshot of an already upgraded ledger.

We are in the process of adding online upgrade support for future versions which will eliminate these upgrade disk requirements.

### Docker tag latest removed¶

As a best security and node management practice, the latest tag for Docker containers has been removed from available tags at https://hub.docker.com/r/nanocurrency/nano. Going forward the only tags available for the live network will be explicit version tags, no dynamically updated tags will be maintained. For this upgrade, the tag V22.0 will be required.

### Upcoming canary block for final votes activation¶

In order for nodes to begin issuing final votes for unconfirmed blocks, and using those votes for cementing blocks, a canary block will need to be distributed to activate the feature. To ensure enough vote weight is prepared for the consensus change, the Nano Foundation will be monitoring upgrades on the network and will distribute the canary block once at least 80% of voting weight is on V22.0+.

### Remove election difficulty sorting¶

Higher work difficulty on blocks will no longer result in increased election priority. Instead, a new election prioritization and scheduling mechanism was designed with initial changes being made in this release. With these changes the work generation is still required for transactions to be valid, but higher difficulties are no longer part of prioritization. Instead, the balance of the account and the time it was last used will be used to determine when elections are started.

For nearly all services and integrations this will have no noticeable impact on how quickly voting will begin on a published transaction. As more improvements are added in V23, addition details will be available about the future of work generation and recommendations for optimizing this in the long term.

### Node count limits per subnetwork¶

The current limits of 5 nodes per IPv4 address is being expanded to include /48 IPv6 subnetwork as well. In addition, a 20 node limit is being applied to the /24 IPv4 range and /32 IPv6 range.

### Node V19.0 or later required¶

Upgrades from versions below V19.0 have been removed from the code base. All nodes must be on at least V19.0 for the upgrade to V22.0 to work. Note that participation on the live network does require at least V21.0 of the node.

To help with handle specific fork situations, the final votes feature will add a second round of voting to the consensus process as follows: once initial voting weight for an unconfirmed block has reached quorum, nodes will issue final votes by setting the timestamp to the maximum integer possible for that field (18446744073709551615). These final votes will then be required to confirm and cement a block in the ledger.

Because this is a consensus change, a network upgrade is required to activate. As noted above, this will be done using a canary block once at least 80% of voting weight on the network has been upgraded. After the canary block is distributed by the Nano Foundation, the final votes will be used for cementing going forward.

RocksDB remains experimental

Previous communications related to RocksDB being approved for production use should be ignored. The RocksDB should still be considered experimental and not recommended for production use.

### Experimental ledger pruning¶

An initial, experimental version of a much requested feature is being made available in V22.0. This feature is NOT for production use. Many of the details can be found in the related pull request, but the main goal is to reduce the disk space required for the ledger by removing blocks not near the frontiers or that are pending sends. Although the final ledger size will be significantly reduced, it does require first downloading the full ledger and then pruning, to ensure integrity of the data. It also is not available for voting nodes, only non-voting nodes will allow this feature.

### Election scheduler and prioritization changes¶

A new election prioritization and scheduling mechanism was designed and the initial updates for this feature are included in this release. These changes will keep work generation as a requirement for transactions to be valid, but switch the election scheduler and prioritization behaviors to use a combination of balance and time since the account was last used. With this approach nodes across the network are expected to see improved performance in clearing the backlog of elections while the network is not actively under spam attack. Future changes in V23 will be targeting improved performance while the network is under load.

## Node configuration and management updates¶

• REMOVAL The online_weight_quorum value, which was used in combination with online voting weight values to determine the voting weight necessary for confirming a block, has been removed as a configuration option and hardcoded to 67% for all nodes. Any existing overrides for online_weight_quorum in the config-node.toml file can be removed.
• The default value for active_elections_size in config-node.toml has been reduced from 50,000 to 5,000. This change was to help limit extra network traffic generated by large amounts of elections as behavior of the active elections container was modified for election scheduler and prioritization needs.

• BREAKING CHANGE All RPCs with the include_only_confirmed option available has that option set by default and setting it explicitly to false will be required to have unconfirmed blocks returned/counted in the response (such as pending amounts or balance amounts). These RPCs include:
• NEW OPTION account_balance
• accounts_pending
• pending
• pending_exists
• wallet_pending
• Option to include_only_confirmed blocks for the returned balance and pending fields was added to account_balance and include_confirmed option to provide extra confirmed_balance and confirmed_height fields for account_info also added (confirmed_height was only added for consistency in naming, as confirmation_height already existed and will be the same value).
• BREAKING CHANGE block_count_type was removed after the database upgrade that merged blocks into the state block format was completed.
• BREAKING CHANGE When both count and sorting options are included in the RPC pending, the result will now be done over all pending blocks before the subset is returned. Previously only a portion of the pending was scanned before returning the requested count.
• RPC bootstrap_any now allows and optional account field for targeting specific account attempt
• RPC bootstrap_lazy now returns more accurate status of whether the bootstrap was started and whether a new lazy key_inserted

• Passing values using the --config command no longer require escaping of quotes
• NEW --migrate_database_lmdb_to_rocksdb does the necessary migration of an existing LMDB database over to RocksDB. Note that after migration the necessary configuration changes to enabled RocksDB must be done to use the new backend.

• Topic confirmation has new optional include_election_info_with_votes which will include the representative, timestamp, sequence, hash, and weight for each of the votes on the election.

## Developer/debug options¶

• When a legacy bootstrap is returned from RPC bootstrap_status, the frontiers_age and last_account will now be included
• NEW CLI --debug_unconfirmed_frontiers outputs the frontier and confirmed (cemented) frontier for any accounts which are not yet fully cemented (warning: could output a lot if used on a ledger with large amount of uncemented blocks).
• New nano_test_network added which is the basis for the new public test network for integration testing (test.nano.org) and allows customizing of various core network parameters to allow for custom test networks to be deployed from scratch.
• C++17 support is now required
• Block rollback messages in logs are no longer available by default to avoid excessive logs in certain scenarios (node.logging.ledger_rollback option to enable)
• Signals available for config file reloading with initial support for bandwidth_limit and bandwidth_limit_burst_ratio options by calling kill -SIGHUP [process #]

## Deprecations/removals¶

• All RPC payment_* removed (previously deprecated in V19.0)
• RPC active_difficuly deprecated due to difficulty not longer being used for prioritization, only for checking validity of blocks
• CLI commands --batch_size and --debug_mass_activity removed (previously deprecated in V21.0)