CertiGuide to A+ (A+ 4 Real)  9  Chapter 10: The Small Computer System Interface, SCSI       9  RAID            9  Internal or External?

Internal or External? 1 External Controller Based

Bus-based raid is defined as an array controlled by a host bus adapter.¹²⁸ The host bus adapter is connected to the server's system bus. A bus-based RAID array can provide a substantial increase in performance and features com-pared to a software-based RAID solution. The host bus adapter can have an embedded processor to manage some or all of the RAID functions and leave the host CPU free to handle application and network processing. This type of intelligent disk array processor can provide improved configuration and man-agement capabilities in addition to performance benefits. The higher cost of an intelligent host bus adapter can be easily justified by the improved per-formance and manageability over software based systems.

However, a bus-based system is still at the mercy of the host system. The RAID array is subject to failure if the host system goes down. The fault tol-erance level of the host server (or lack thereof) can become the weak link in your RAID array.

Internal or External? 1 External Controller Based