Quote from documentation:
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Raiding dirs for archiving purposes
The contents of two or more dirs can be merged as shown below.
Note: For read-only purposes! Writing is however possible, uploaded files (in a raided VFS dir) will be stored on last device specified.
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Would it be possible, regarding uploads, to make it choose the drive/dir with most space left?
With the new dvdr frenzy and increased bandwidth, 2 drives with identical content isn't really that uncommon.
Perhaps too resource demanding and unimportant for most but, just a thought