Apparatus and method for managing metadata in a data storage device. In some embodiments, a metadata object has entries that describe data sets stored in a non-volatile write cache. During an archival (persistence) operation, the metadata object is divided into portions, and the portions are copied in turn to a non-volatile memory at a rate that maintains a measured latency within a predetermined threshold. A journal is formed of time-ordered entries that describe changes to the metadata object after the copying of the associated portions to the non-volatile memory. The journal is subsequently stored to the non-volatile memory, and may be subsequently combined with the previously stored portions to recreate the metadata object in a local memory. The measured performance latency may be related to a specified customer command completion time (CCT) for host commands.