Extended Ephemeral Logging (XEL) is a database logging and recovery technique which manages a log of recovery data by partitioning it into a series of logically circular generations. XEL copies longer-lived log data from one generation to another in order to reclaim more quickly the space occupied by shorter-lived log data. As a result of copying, records in the log lose their original ordering; this leads to main-memory and log space overhead for obsolete recovery data. In this paper, we quantify the e_ects of reordering log records by introducing the notion of Garbage Removal Dependencies (GRDs). We develop a classi_cation of log records based on GRDs and use it to characterize main-memory and log space allocation during normal system operation. Through simulation, we demonstrate how main-memory and log space allocation vary with changes in database and workload parameters.