In an approach for taking corrupt portions of cache offline during runtime, a notification of a section of a cache to be taken offline is received, wherein the section includes one or more sets in one or more indexes of the cache. An indication is associated with each set of the one or more sets in a first index of the one or more indexes, wherein the indication marks the respective set as unusable for future operations. Data is purged from the one or more sets in the first index of the cache. Each set of the one or more sets in the first index is marked as invalid.