All the raid configurations you mention are fault tolerant, they can lose 1 drive, raid 10 possibly more, without a hotspare. Hot spares just add to the safety of arrays, they will become an full functioning active member of an array should a drive fail. Hotspares have nothing to do in creating or maintaining parity, no array must have a hotspare (at least not in the general consumer class of raids). Personally I institute a hotspare for most of my client's arrays, takes the pressure off me to replace a failed drive, adds a margin of safety. "And somebody stated that for R5 you need to have hot spare in order for the array to have Fault Tolerance." That "somebody" need some basic raid knowledge, Raid 5 does not need a hotspare to have fault tolerance, it can lose 1 disk, then it runs in degraded mode until the faulting/dead disk is replaced and the rebuild process completes.   
Hello Dell And others,   Good Day.   I know this is a low brainer but I appreciate any feedback. This is about Raid Array having hot spares. 1. Raid 1 (Mirroring) Does raid 1 need hot spare to perform fault tolerance?   2. Raid 10 (Stripe and Mirror) For Example, I have 4 SAS Drives configured in Raid 10, Does This one also need a hot spare to perform HA?   3. Raid 5 (Striping) I Have 3 HDD (600 GB Each) configured in Raid 5 with a logical volume capacity around 1.2 TB. Do I need to have a hot spare for this one in order for the parity to perform HA?   I Hope you can help me with my confusions.   Thanks a lot!        
RAID CONFIGURATION WITH HOT SPARE