Low price Only requires a standard controller. External Hardware RAID Card Connects to the server via a standard controller. RAID functions are performed on a microprocessor located in the external RAID storage subsystem. Two or more hard disk drives grouped together to appear as a single device to the host computer. A temporary, fast storage area that holds data from a slower storage device for quick access.
Cache storage is normally transparent to the accessing device.
Duplexing Mirroring across two RAID cards. The ability of a system to continue to perform its functions even when one or more hard disk drives have failed. Hot Spare A spare hard drive which will automatically be used to replace the failed member of a redundant disk array. The ability to remove a failed member of a redundant disk array and replace it with a good drive without bringing down the server or interrupting transactions that involve other devices. Microprocessors offer higher performance compared to co-processors.