If you use the store-through cache method, you write copies of the same data to the cache structure and permanent storage. Therefore, when you write a changed data item to the cache structure, you indicate on the write request that the data item is unchanged because, at the same time, you intend to write the same data item to permanent storage. (Remember that data is considered changed in a cache system when any copy of the data in the cache structure has been updated and is no longer the same as the data in permanent storage.) Using IXLCACHE, you can also request the cast-out lock for the data item to serialize the update to permanent storage, and request that the system invalidate copies of the data item in the local buffers of the other users.