A logical representation of one or more physical disks configured to provide redundant and/or large storage space for the system.
RAID 1
They are both the same thing.
Mirrored Volume
Volume is an old audio and music term, and its use in TV is merely carried over from radio. It only applies to the sound component, not the video component.
A dekaliter is 10 liters, so a volume .01 of a dekaliter is 1 deciliter (0.1 liter).