Flexible, scalable services on massive geo data receive much attention today. In particular, the OGC Web Coverage Service (WCS) standards suite has established a best practice for versatile access and retrieval on spatio-temporal "Big Data". Fewer efforts have been devoted, though, to an easy-to-use, standardized way of maintaining a service's offering. Our experience from supporting a series of heterogeneous, large-scale services reveals that this can become tedious indeed, due to heterogeneity and incompleteness of incoming data, operator-less transformation and ingest of large amounts of files, as well as the need for narrowly focused manual corrections and updates sometimes.In this contribution, we present the WCS-T (for "Transaction") specification which enables users and machines to perform atomic insertion, updating, and deletions through simple Web requests. WCS-T has been implemented and is actively being used in projects; recently, it has entered the adoption process in OGC to become part of the WCS suite.