Once I run out of space will I be able to add one or more hard drives
to expand the storage? If yes how would I do that (I don't see any
relevant instructions in the manual)?
It depends of what features you motherboard supports. To expand a RAID array, it may be necessary to reallocate the data and resync the disks to accommodate the new array. So I would not rely on it.
Will it be feasible to change motherboard and keep RAID5 setup alive
(I don't see attach existing RAID5 option in my mobo's manual, so
maybe it will be absent in my next mobo as well)?
Probably no. Hardware RAID implementations are very hardware-dependent. I doubt there is a standard on how to implement a RAID, so each vendor does its own implementation. One should think the RAID levels are a low-level standard, but they are, in fact, a conceptual description of how the array organizes data. The low-level implementation may be different so the RAID arrays are mostly not interchangeable. If you implement a RAID array with a specific controller, that array will probably only work with that controller.
In event of death of one of my drives, will it be feasible to
gracefully replace it with a new one with current setup (again, I
can't find any instructions for such case in manual)?
If one of your drives fail (remember that RAID-5 only supports the failure of one drive at once), there are two possible situations:
- You don't replace the failed drive. The array will be degrated but it will work. The controller will rebuild the data from the missing drive using the parity information and keep your data available, even without the failed disk. No action is needed. The RAID array setup will display a missing spot in the array. In this situation, if another drive fails, your data is lost.
- You replace the failed drive. First, nothing happens. It is just a new disk in the system, available to the OS. You will need to tell the controller that drive is part of the degrated array in the RAID setup (some controllers forces the replacing drive to be exactly the same, the size, the brand, the model, so be warned). After this, the array will start a process to resync the disks, copying data to the new drive and calculating new parity bits as necessary. At the end of this process, the array will lose its degrated status and be fail-safe again.
I feel that for a home-based implementation of RAID, you should avoid hardware RAID implementation and rely on a RAID implementation based in software. They are not that evil as many think they are (the performance gain are almost the same), they are easier to handle, and they are much more interchangeable with new hardware than any hardware implementation. So think about it. :-)
Windows offers software RAID implementations in Windows 10. To build a RAID-5 you should use the layout "Parity". I am just not sure if this feature is restricted for some editions of Windows (since you use Windows 10 Home edition), so you will need to check.