A determination is made of a track to demote from the first cache to the second cache, wherein the track in the first cache corresponds to a track in the storage system and is comprised of a plurality of sectors. In response to determining that the second cache includes a the stale version of the track being demoted from the first cache, a determination is made as to whether the stale version of the track includes track sectors not included in the track being demoted from the first cache. The sectors from the track demoted from the first cache are combined with sectors from the stale version of the track not included in the track being demoted from the first cache into a new version of the track. The new version of the track is written to the second cache.