Does this include some kind of built-in hash/checksum system to record e.g. md5 sums of each file and periodically test them? I have a couple of big drives for family media I'd love to protect with a bit more assurance than "the drive did not fail".
This is not strictly accurate. ZFS records checksums of the records of data that make up the file storage. If you want an end to end file-level checksum (like a SHA-256 digest of the contents of the file) you still need to layer that on top. Which is not to say it's bad, and it's certainly something I rely on a lot, but it's not quite the same!
Does this include some kind of built-in hash/checksum system to record e.g. md5 sums of each file and periodically test them? I have a couple of big drives for family media I'd love to protect with a bit more assurance than "the drive did not fail".