A case for virtualized arrays of RAID

Redundant arrays of independent disks, also called RAID arrays, have gained a wide popularity in the last twenty years. Most of the disks used in the server market are currently based on RAID technology. The primary reason for introducing RAID technology in 1988 has been the fact that large disk systems have become much slower and more expensive than the connection of a large number of inexpensive disks and the use of them as an array. The times seem to repeat themselves. Today, large scale RAID arrays have become incredible big and expensive. It seems that it makes sense to replace them by a collection of smaller and inexpensive arrays of JBODs or mid-ranged RAID arrays. In this paper we will show that combining these systems with state-of-the-art virtualization technology can lead to a system that is faster and less expensive than an enterprise storage system, while being as easy to manage and as reliable. Therefore we will outline the most important features of storage management and compare there realization in enterprise class storage systems and in current and future virtualization environments.