HP Surestore Disk Array 12h System Administrator's Guide for HP-UX, MPE, and W - Page 18

HP-UX Managing the HP SureStore E Disk Array 12H on HP-UX Tips for Configuring the Disk Array On HP-UX Configuration Option Number of disk drives Unallocated disk array capacity LVM configuration Impact on Performance and Capacity Performance. Increase the number of disk mechanisms in the disk array for maximum performance. As the number of individual disks is increased, the number of potential I/Os that can be performed simultaneously increases as well. This will improve performance in environments that place heavy I/O demand on the disk array. Capacity. The capacity of a disk array that is fully populated with disk mechanisms can only be increased by replacing lower capacity disks with higher capacity disks. Performance. Unallocated capacity is used as additional RAID 0/1 space. The amount of RAID 0/1 space required to maintain optimal performance is determined by the write working set parameter. Capacity. To create the maximum amount of storage capacity, allocate all available capacity to LUNs. Performance. To improve performance, configure LVM as follows: • Stripe logical volumes across LUNs on different disk arrays. Including LUNs on different disk arrays will improve throughput by spreading I/Os across arrays. • Divide LUN access between both disk array controllers. Mapping every LUN to the same controller does not utilize the two data paths available on the disk array. The default path is through the primary disk array controller, but this can be changed to the secondary controller when adding the physical volume to an LVM volume group. The process for changing the path differs for each version of HP-UX: HP-UX 10.1. From the Disk Devices list, select the disk hardware path through the secondary controller before adding the disk to a volume group. HP-UX 10.2. When adding the disk to a volume group, in the "Creating A Volume Group" dialog change the hardware path to the secondary controller Capacity. These LVM configurations have no impact on disk array capacity configuration. 18