I noticed that my newly formatted set-up (raid5) shows that around 10% of the space is used. I have written no files to the drive. All hard drives are the same size and I set data to 100% and usb to 0% when configuring. Is this normal? (I am new to the whole raid scene?)
No, I don't think the N5200 is setup to do alot of swapping. It should survive more or less on the physical RAM it has installed.
But since the filesystem at the bottom is EXT3 I guess this "lost" space is used for inodes. And since inode-configuration of the filesystem is done at creation-time (creation of RAID) it has to fit most of the usage the system will "see".
So I think this 10% overhead is caused by administrative objects for the EXT3-filesystem: * Journal-space for EXT3 * Inodes for EXT3