# EPF6 Dev Updates – Week 5 This week I explored Lighthouse codebase for the backfill implementation. Got some idea about the basic flow and organization. As I'm quite new to Rust so I'm trying to get more familiar with the syntax and rust specific concepts such as ownership, borrowing, traits, options, lifetimes, etc which are being used frequently in the codebase obviously due to performance requirements. I was researching about how exactly lighthouse prevents db holes while backfilling, got some thoughts in the lighthouse discord and also went through some prs related to blobs backfilling shared by sproul from lighthouse team https://github.com/sigp/lighthouse/pull/6656, https://github.com/sigp/lighthouse/pull/7751. Completed the basic backfill algo ([hackmd](https://hackmd.io/@vedant-asati/S1lBv14Llx)), got positive feedback from my mentor from lodestar (matt) but then he suggested to break down the entire backfill task in different subtasks for simplicity ([here](https://github.com/ChainSafe/lodestar/issues/7753#issuecomment-3079263617)) so I decided to stop the work there only. Also presented my project presentation ([slides](https://docs.google.com/presentation/d/1RJglT1r2KXq9Wkt-YGHKOBjXQOtyHSIsdnzBPi-7yAU/edit?usp=sharing)) in epf office hours. Still struggling with running EL+CL combinations. Week 6 goals: --- - Lighthouse deep dive - Retry running EL+CL combinations