For inserts, Kangaroo first inserts objects into the DRAM cache (1). Objects evicted from the DRAM cache are either dropped by a pre-flash admission policy (2a) or added to KLog’s DRAM index (2b) and appended to KLog’s flash log (2c). Objects evicted from Klog are either (3a) dropped by another admission policy (3a) or inserted to KSet (3b).