Patent attributes
Embodiments are disclosed for a multi-tier storage system. The techniques include identifying a candidate extent stored in a first tier of a first storage pool of a multi-tier storage system (MTSS). The candidate extent is blocked from promotion because of a space constraint on a second tier. The techniques also include identifying a second tier of a second storage pool. The second tier provides faster input-output (I/O) access than the first tier provides. Additionally, the second pool includes available space to store the candidate extent. The techniques further include copying the candidate extent to the second tier of the second storage pool. The techniques also include generating a cross-pool mapping. The cross-pool mapping maps from a first address of the candidate extent in the first tier of the first storage pool to a second address of the copied candidate extent in the second tier of the second storage pool.
