---
# System prepended metadata

title: EPF6 Dev Updates – Week 2

---

# EPF6 Dev Updates – Week 2
This week I deep dived into Grandine db implementation & Lodestar codebase and finally decided to work on backfill implementation in Lodestar. 

I went through syncing mechanisms in detail:
https://chainsafe.github.io/lodestar/run/beacon-management/syncing
https://lighthouse-book.sigmaprime.io/advanced_checkpoint_sync.html

Revisited weak subjectivity: https://notes.ethereum.org/@adiasg/weak-subjectvity-eth2#Weak-Subjectivity-in-Eth20 
https://blog.ethereum.org/2014/11/25/proof-stake-learned-love-weak-subjectivity
https://www.symphonious.net/2019/11/27/exploring-ethereum-2-weak-subjectivity-period/

Lodestar already has some backfill related implementation (https://github.com/search?q=repo%3AChainSafe%2Flodestar+backfill&type=code). I explored more to know what exactly to be done as current epf project.

I went through the code, mainly https://github.com/ChainSafe/lodestar/tree/unstable/packages/beacon-node/src/sync/backfill

I'm not very sure about it, but will explore more.

Revisited carefully: https://github.com/ChainSafe/lodestar/issues/7753

Realised that we need to backfill blobs along with blocks. Backfilling blobs needs additional requirements, considering peerDAS (https://eips.ethereum.org/EIPS/eip-7594). Also, as it is not implemented in lodestar. I might also need to look more about current peerDAS implementation.


Week 3 goals:
---

I'll explore more about peerDAS and its existing implementations next week.

Also explore more resorces about backfilling, deep dive into other parts of code in lodestar and in other clients (lighthouse, teku).
Try to understand the overall architecture of lodestar and start working on the proposal next week.

I'm also planning to do open source contributions in lodestar to get more familiar with the codebase.