Storing and retrieving render output

A graphics processing apparatus comprising graphics processing circuitry, a storage control unit and storage, wherein the storage comprises a plurality of storage regions, and wherein the graphics processing circuitry is configured to carry out a method comprising:

• producing, by the graphics processing circuitry, an updated render output, wherein the updated render output corresponds to at least a portion of an previous render output, and wherein at least a portion of the previous render output is stored as a data unit in the storage, wherein the data unit comprises header data and body data, wherein the body data is stored in a first storage region of the plurality of storage regions and the header data is stored in the storage, wherein the header data comprises a reference to the first storage region;
• and
• storing, by the storage control unit, at least a portion of the updated render output in the storage by:
• inspecting the reference to the first storage region in the header data of the data unit;
• selecting a storage region of the plurality of storage regions as a second storage region, wherein the second storage region is selected based on the reference to the first storage region in the header data and wherein the second storage region and the first storage region are different storage regions of the plurality of storage regions;
• storing updated body data corresponding to the updated render output in the second storage region;
• and
• updating the header data in the storage such that the reference in the header data is a reference to the second storage region.