Optical drive

storage.opticalHands-on · automaticHigh confidence

How it tests

Offered when the quick pass finds the Mac's own drive with its block device (sr_mod). Asks the drive for its state until it holds a disc, then reads it: a data disc's first MB through the drive, opened read-only, or an audio CD's table of contents. Then it ejects the disc (slot-loading drives have no button) and waits until the drive reports it gone. Nothing is mounted or written. The sleep tests wait until the drive is empty, since a Mac can hang going to sleep with a disc in it.

How it decides

Supported: the disc read and came back out. Partial: it read but wouldn't come out. Failed: the drive couldn't read two discs (a read that stalls for 20 s or runs past 90 s counts as one), or a disc went in and the drive never reported it (“Nothing happens”, after 25 s). A Mac that came with a drive and has none now isn't failed: it may have been removed or swapped for a disk.

How sure it is

Reading a disc and ejecting it takes the whole drive: loading, the laser, its link to the Mac and the eject.

What could mislead it

Could pass when it shouldn'tAn audio CD has only its table of contents read, not its tracks.
Could fail when it shouldn'tTwo damaged discs fail a working drive.