A decade or two ago, a single server might have had up to 500 GB of hard drive space contained internally, possibly made up of 3-4 hard drives operating as a single volume. The cost to do this was still very high, so companies would often opt out of purchasing any redundant drives or systems, and instead rely on tape backups for disaster recovery. Tapes took a really long time to do full backups and sometimes failed when used to recover lost files. Over the years, hard drives have grown in capacity, stability and affordability, and demand for larger volumes of storage space has also increased. One technology that has been used for storage is RAID. How is this technology implemented in company data centers today? Do companies buy servers with large volumes of internal storage space? Or do they tap in to more centralized storage? Why?