Examples disclosed herein relate to determining that an operation is accessing data on a persistent memory and retrieving a log of the operation. The examples may also include determining a type of the data being accessed by the persistent memory by the operation and identifying, from the log, a location in the persistent memory of the data accessed by the operation. The examples may also include determining contents of the data accessed by the persistent memory by the operation and determining whether the contents of the data hold an invariant corresponding to the type of data.