MemoryStorage can be setup using NewMemoryStorage(size). A RWMutex is used to ensure safety. If you wish to support concurrent writes, one way would be to use a ShardedStorage module to split the memory into several blocks which can then be written to concurrently.
FileStorage can be setup using NewFileStorage(f, size) for an existing file, and NewFileStorageCreate(f, size) if you wish to create a new file.
FileStorageSparse can be setup using NewFileStorageSparseCreate(f, size, blockSize) for creating a new file. Only blocks which have been written to are stored in the file. Only supports reads for blocks that have already been written. Partial block reads are supported. Partial block writes are discarded.