Enable Warp Sync

[wilwade]

Warp sync allows fast syncing and is currently not working. After #1270, we should be able to enable it.

Related:

• Moonbeam Upgrade PR that enabled warp sync for them with 0.9.40: Dependency (Substrate/Polkadot/Frontier/Cumulus/...) update to v0.9.40 moonbeam-foundation/moonbeam#2202
• Polkadot PR enabling Warp Sync: Companion PR for warp sync support. paritytech/polkadot#3382

Note that warp sync does not work on the Rococo Relay chain (although still works on the Frequency Testnet)

• https://substrate.stackexchange.com/questions/9730/rococo-cant-warp-sync-stuck-at-16mb-finality-proof-download

[rlaferla]

https://spec.polkadot.network/chap-sync

[rlaferla]

How do we test warp sync to ensure integrity of data and consensus?

[wilwade]

The security is based on the relay chain peering. If we have a state with a root that matches one on the relay chain, then we know that state is good.

For warping the relay chain, it is almost the same, except it is that the additional blocks are built on the warp'd block.

While it is possible to chose a bad warp provider it is no different that choosing a bad chain spec or connecting to a bad bootnode.

[rlaferla]

It's not clear that Warp sync will work with Aura consensus but there are examples of it working with Grandpa. More research is needed.
https://substrate.stackexchange.com/questions/9484/how-to-enable-warp-sync-with-aura-consensus

[wilwade]

Appears to be possible: paritytech/cumulus#1909

Yup added in v0.9.39: https://forum.polkadot.network/t/polkadot-release-analysis-v0-9-39/2277#add-warp-to-target-block-for-parachains-10