javadb - simple implementation db from book. links leveldb
BigTable

development plan
1 - simple key value storage
2 - memory cache for storage file with shifted 3 - storage byte on the disk 4 - ss tables
5 - move full log file to ssTable file, create new file, remove old log file 6 - compaction file into 1 file 7 - recovery process from log file to Memtable after crashed app