While working on EC I found working on the LOD layer a challenge. The code to handle moving between struct lov_user_md and struct lod_layout_compnent was redone several times independent of each other. This means PFL behavior was implemented inconsistently. For example adding a component doesn't support a new component that has specific OST selection.

The second improvement is moving ldo_comp_entries from a large array to a Xarray. This makes management of layout changes much easier. Another benefit is that the Xarray support multi-tiering. This means we can 'link' a parity component to a data component.