Now that we know the ins and outs of managing storage, we must face a simple and uncomfortable truth: disks fail. It's not a matter of if, but when—all disks will fail eventually. When they do, we rely on our backups and disaster recovery procedures to get up and running. One thing that can help us with this burden is RAID, which is an acronym for Redundant Array of Inexpensive Disks. The basic idea of RAID is that when a disk does fail, we don't lose any data (unless additional disks fail) and we'll continue on without any significant downtime assuming we replace the disk within a reasonable time frame. This isn't used as a backup, but it is a nice safety net in a situation where we lose a disk.
There are two types of RAID, hardware RAID and software RAID. With hardware RAID, the operating system is completely oblivious to the fact...