Add EIP: Cease serving history before PoS

EIPS/eip-7639.md

@@ -0,0 +1,55 @@
+---
+eip: 7639
+title: Cease serving history before PoS
+description: Execution layer clients will no longer serve block data before Paris over p2p.
+author: lightclient (@lightclient)
+discussions-to: https://ethereum-magicians.org/t/cease-serving-history-before-pos/18991
+status: Draft
+type: Standards Track
+category: Networking
+created: 2024-02-13
+---
+
+## Abstract
+
+Execution layer clients will no longer request or respond to p2p queries about
+block data before the Paris upgrade.
+
+## Motivation
+
+As of 2024, historical data in clients has grown to around 500 GB. Nearly 400 GB
+of that is from block data before PoS was activated in the Paris upgrade. Long
+term, Ethereum plans to bound the amount of data nodes must store. This EIP
+proposes the first steps to achieve such goal.
+
+## Specification
+
+Clients must not make or respond to p2p queries about blocks before block 15537393.
+
+## Rationale
+
+### Only Pre-PoS data
+
+One might ask why the distinction between pre and post PoS data is made in this
+EIP. The simple answer is that the at the moment of the merge, the block
+structure changed substantially. Although execution layer client software today
+continues on with block data on disk which remains similar to per-PoS data, the
+beacon chain is now the canoncial chain definition. Therefore, a beacon block
+can be used to both record historical data for execution layer and beacon layer.
+
+Over the long term, the distinctions of "execution layer" and "consensus layer"
+may matter less. This EIP tries to be agnostic to client architecture and
+instead focuses on the shape of the data.
+
+## Backwards Compatibility
+
+After this EIP is activated, nodes will no longer be able to full sync from the
+devp2p network. To continue doing so, they must retrieve the data out-of-band.
+
+## Security Considerations
+
+TODO
+
+## Copyright
+
+Copyright and related rights waived via [CC0](../LICENSE.md).