Does extstore also use the same slab allocator that memcached does in memory? Cause if so I feel that disk usage might actually be worse than imagined due to the slab packing problems. I think the design decision to keep everything in memcached makes a lot of sense, but RocksDB seems like an odd choice for the first iteration. It’s big claim to fame is durability while achieving high performance, and it shines in situations like MyRocks, but for caching, especially where replication is handled on top of the things writing to disk, that doesn’t seem as important. I think extstore also does compaction but on a 64M page by page basis instead of using one big log.