A method, computer program product, and system includes a processor(s) obtaining historical data related to buffer space usage of a common shared storage resource by a group of journals. The processor(s) monitors each journal over repeating temporal periods and determined a predictability for each journal (i.e., predictable or unpredictable. The processor(s) generates usage statistics for each journal during each monitored period dependent on whether the journal was predictable or unpredictable during the monitored period. For each monitored period, the processor(s) ranks predictable journals by a buffer space requirement for each journal of the predictable journals. Based on the rankings, the processor(s) determined a buffer space requirement for each journal for a current period, where the current period shares temporal qualities with the given monitored period. The processor(s) allocates, for use during the current period, based on the buffer space requirement, buffer space to each journal.