Unlike many competing apps, DaisyDisk is capable of scanning multiple disks and folders at a time. This can be a real time saver when you perform regular disk maintenance.
However, it is not the case when you scan multiple volumes of the same hard disk in parallel, because the head of the hard disk has to make a lot of extra jumps. In order to reduce hardware load and speed up scanning, DaisyDisk automatically scans such volumes one by one rather than simultaneously. It also visually groups volumes of the same disk together, so you can tell when two volumes belong the same physical device.
Unlike HDDs, SSDs don’t have moving parts. DaisyDisk automatically detects SSD drives and does not prevent parallel scanning on them.