Recently, I had to go through crash recovery of a large MariaDB 10.1.21 instance. After starting MariaDB, I started tailing the error logs expecting to wait many minutes while InnoDB was scanning ibd files. I was surprised (and actually delighted) with this:
[...] [...]:34:36 [...] [Note] InnoDB: Reading tablespace information from the .ibd files... [...]:34:53 [...] [Note] InnoDB: Processed