Hi,
Due to the nature of how RAID 5 stripes data and parity, you can only recover if one hard drive has failed. Two hard drive failures and you are out of business.You don't see many consumer RAID 5 configurations as it typically takes up too many SATA ports.
In a more robust commercial environment, a RAID 10 configuration that includes hot standby hard drives is perhaps the safest RAID configuration. When a hard drive fails then the standby hard drive is automatically configured into the array. RAID 10 will protect you against two hard drive failures. Synchronizing the array via a remote link to a remote site should protect you against a local disaster.