HP Surestore Disk Array FC60 HP SureStore E Disk Array FC60 Service Manual (A5 - Page 69
High Availability, Performance, Channel host I/O adaptors
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Topology and Array Planning High Availability If your application requires high availability, you should implement the options discussed here. To configure the array for high availability, there must be no single points of failure. This means that the configuration must have at least these minimum characteristics: • Two controllers connected to separate Fibre Channel loops (using separate Fibre Channel host I/O adaptors) • Two disk enclosures (minimum) • Four disk modules, two in each disk enclosure (minimum) • Volume groups that use only one disk per disk enclosure. With its dual controllers, the Disk Array FC60 provides two independent I/O paths to the data stored on the array. Data is transmitted from the array controllers to the disks through up to six Ultra2 SCSI channels connected to the disk enclosures. Any of several RAID levels (1, 0/1, or 5) can be selected, however, for the greatest high availability, It is recommended that RAID level 1 be used for optimum high availability. Performance The maximum aggregate performance that can be sustained by the disk array is approximately 170 megabytes per second (using dual Fibre Channel-AL connections). This performance can be achieved by configuring at least four disk modules per Ultra2 SCSI bus utilizing the six Ultra2 SCSI channels. This can be accomplished in two ways. One way is to configure six disk enclosures, one each per Ultra2 SCSI channel (disk enclosure full-bus mode). In each of these enclosures, configure at least four disk modules. Adding more disk modules to each of these disk enclosure will increase storage capacity, but will not appreciably increase the sequential thoughput. Additional capacity may be a worthwhile addition, since in many computing environments, capacity, not access speed, is the limiting factor. Another way to configure for maximum performance is to connect three disk enclosures to the controller enclosure and configure these enclosures for split-bus operation. Then connect an Ultra2 SCSI channel to each split bus (two channels per disk enclosure). Each of the buses must be configured with at least four disk modules (eight disk modules per Array Design Considerations 69