Compaq ProLiant 8500 ProLiant 8500 Server Technology - Page 18

TECHNOLOGY BRIEF (cont.) RAID - Redundant Array of Independent Disks TC000604TB ... Integrated Array Controller Technology The Compaq ProLiant 8500 server is equipped with an Integrated Smart Array Controller. The integrated controller, also known as RAID on a chip, or ROC, is an embedded hardware-based RAID solution that enhances system reliability and improves host processor utilization. It is ideal for data center servers, like the ProLiant 8500 server, in which internal storage is optimized for OSs and swap space. RAID implementation enhances data integrity and recovery through data striping and parity generation for the data rebuild process. The integrated array controller improves host processor utilization by performing all RAID functions, thus freeing the host processor for other tasks. The controller is fully integrated and embedded on the motherboard of the ProLiant 8500 server, which improves I/O efficiency and frees a PCI slot for another controller. The integrated controller can also queue tasks and data, thereby increasing performance. The integrated controller consists of a processor, memory controller and hardware exclusive-OR (XOR) engineer, SCSI chip, PCI bridge, and an internal bus structure embedded on a single substrate. The controller has fewer parts than typical array controllers, since all of the components and connections are combined into one integrated circuit. Fewer parts leads to greater reliability and increases mean time between failures. The integrated array controller includes a 16-MB read-only memory, with an 8-MB read-ahead cache. This memory configuration is optimal for OS and boot support. Since the memory is read only, data loss is not an issue and battery backup is not required. This controller provides two Wide Ultra-2 SCSI channels. One channel is dedicated to the internal drive bay. The other channel is connected to the external SCSI connector. It uses a high-density connector, and only supports tape backup devices. The integrated array controller in the ProLiant 8500 server can be bypassed using an Integrated Array Bypass Kit and an optional controller, such as the Compaq Smart Array 3200 controller. A bypass kit is shipped standard with all ProLiant 8500 servers. Although the ProLiant 8500 server supports Wide Ultra-3 SCSI hard drives, the drives will run in Wide Ultra-2 mode with the Integrated Smart Array Controller. An optional Wide Ultra-3 SCSI array controller can be used with the bypass kit to provide Wide Ultra-3 speeds; however, the Integrated Smart Array Controller provides out-of-the box RAID capability with maximum transfer rates of 80 MB/s, allowing optimum OS and boot support. Configuration Utilities The Option ROM Configuration for Arrays Utility is firmware that comes with the integrated controller in the ProLiant 8500 server. This firmware allows users to set up a simple configuration during POST. The support includes the ability to create a single logical drive, delete a single existing logical drive, view the current configuration, and assign an online spare as part of the logical drive creation process. The integrated controller may be configured to initialize as an intelligent I/O processor supporting either dual-channel SCSI operation or RAID. For more advanced configuration support, Compaq provides the Array Configuration Utility. The Compaq Array Configuration Utility is an easy-to-use graphical configuration utility to help users set up and change drive array configurations. It can be used to configure the standard internal drive controller as well as any optional controller boards that are installed. RAID Support The integrated array controller supports RAID levels 0, 1, 0+1, and 5 to ensure data integrity and availability. When configured for RAID 5, and prior to any possible drive failure, the controller 18