Embodiments are disclosed for a multi-tier storage system (MTSS). The techniques include identifying a first data extent stored in a first storage pool of MTSS based on a read-write heat mapping by the MTSS. The first data extent is associated with a mirrored volume. The first data extent is a mirrored copy of a second data extent stored in a second storage pool of the MTSS. The first storage pool is asymmetric to the second storage pool. The techniques also include determining that a second top promotion tier of the second storage pool is faster than a first top promotion tier of the first storage pool. The techniques further include promoting the second data extent to the second top promotion tier based on the determination. Additionally, the techniques include updating an I/O access policy to direct future I/O operations for the mirrored volume to the second data extent.