Storage: Disk Arrays
Transcript
A single disk is expected to provide some basic functionality and for the most part does so quite well. That is provide a simple storage location where there are no needs for high performance or redundancy. However, once we start getting into demands for higher performance and increased protection from drive failures and data loss, we need to start considering moving beyond the single disk into what we call, a disk array. A disk array is a linked group of one or more physical hard drives. The disk arrays are sometimes implemented as single daisy chain configurations but are more commonly implemented as RA ! technologies which stands for Redundant Array of ndependent !isks. This is why we sometimes refer to !isk Array "ontrollers as RA ! "ontrollers. A disk array may contain a few disks in a simple configuration or up to several disk drive trays in multiple drives in a large configuration. !isk arrays are typically implemented to improve speed and performance as well as increase the level of protection against data loss. !isk arrays are implemented with the use of a !isk Array "ontroller "ard which is installed in the computer and connected to multiple disk drives as shown here. At that point, management software is used either during the boot up process or prior to the operating system installation, or from within the operating system itself to create and manage the disk array. The advantages of using disk arrays over single disk drives, is that a disk array organi#es the disk storage into logical units. These appear to the operating system as typical disk drives but the hardware in the background is spreading the data across many physical hard drives to increase the performance for read and write operations. t also provides protection against disk drive failures by maintaining multiple copies of the data on disk while seamlessly presenting a single view of the data to the operating system. !isk arrays are an integral part of high performance storage systems. And their importance and scale are growing as continuous access to information becomes critical to the day$to$day operation of modern business. This has been an overview of storage disk arrays, thanks for watching.