Abstract: Decreasing disk costs make it possible to take frequent snapshots of past storage system states and retain them for a long duration. Existing snapshot approaches offer no satisfactory solution to long-lived snapshots. Split snapshots are an approach that is promising because it does not disrupt the current state storage system in either the short or the long run. An unsolved problem has been how to maintain an efficient access method for long-lived split snapshots without imposing undesirable overhead on the storage system. Skippy is a new approach that inexpensively indexes long-lived snapshots in parallel with snapshot creation. An embodiment of Skippy uses append-only index data structures to optimize writes while simultaneously providing low-latency snapshot lookup. Performance evaluations of Skippy indicate that this new approach is effective and efficient. It provides close-to-optimal access to long-lived snapshots while incurring a minimal impact on the current-state storage system.

Abstract: Decreasing disk costs make it possible to take frequent snapshots of past storage system states and retain them for a long duration. Existing snapshot approaches offer no satisfactory solution to long-lived snapshots. Split snapshots are an approach that is promising because it does not disrupt the current state storage system in either the short or the long run. An unsolved problem has been how to maintain an efficient access method for long-lived split snapshots without imposing undesirable overhead on the storage system. Skippy is a new approach that inexpensively indexes long-lived snapshots in parallel with snapshot creation. An embodiment of Skippy uses append-only index data structures to optimize writes while simultaneously providing low-latency snapshot lookup. Performance evaluations of Skippy indicate that this new approach is effective and efficient. It provides close-to-optimal access to long-lived snapshots while incurring a minimal impact on the current-state storage system.