• Low price
• Only requires a standard controller.

Unlike software-based arrays, bus-based array adapters/controllers plug into a host bus slot [typically a 133 MByte (MB)/sec PCI bus] and offload some or all of the I/O commands and RAID operations to one or more secondary processors. Originally used only with mid- to high-end servers due to cost, lower-cost bus-based array adapters are now available specifically for entry-level server network applications.

In addition to offering the fault-tolerant benefits of RAID, bus-based array adapters/controllers perform connectivity functions that are similar to standard host adapters. By residing directly on a host PCI bus, they provide the highest performance of all array types. Bus-based arrays also deliver more robust fault-tolerant features than embedded NOS RAID software.

As newer, high-end technologies such as Fibre Channel become readily available, the performance advantage of bus-based arrays compared to external array controller solutions may diminish.

• Data protection and performance benefits of RAID
• More robust fault-tolerant features and increased performance versus software-based RAID.

Intelligent external array controllers "bridge" between one or more server I/O interfaces and single- or multiple-device channels. These controllers feature an on-board microprocessor, which provides high performance and handles functions such as executing RAID software code and supporting data caching.

External array controllers offer complete operating system independence, the highest availability, and the ability to scale storage to extraordinarily large capacities (up to a terabyte and beyond). These controllers are usually installed in networks of stand alone Intel-based and UNIX-based servers as well as clustered server environments.

• OS independent
• Build super high-capacity storage systems for high-end servers.