HP Surestore Disk Array FC60 HP SureStore E Disk Array 12H User's and Service - Page 100

Concepts and Management Managing the Disk Array Capacity Managing the Disk Array Capacity This section explains how to manage your disk array efficiently. It concentrates on two primary management tasks: managing capacity and optimizing performance. The overall capacity of the disk array can be configured in a variety of ways. Depending on your system needs, you can configure the disk array capacity to provide maximum available capacity, improved performance, or optimum protection from disk failure. The entire capacity of the disk array is divided into several categories, each playing a different role in the operation of the array. To manage array capacity efficiently, you should understand what each of these categories do. • Logical Drive (LUN) - capacity assigned to the logical drives (LUNs) created on the array. This is the capacity visible to the operating system. You must create the desired logical drive configuration on your disk array, observing any specific limitations and requirements imposed by your operating system. Each logical drive appears to the operating system as a separate disk drive. The capacity for each logical drive is distributed across all the disks in the array. • Data Redundancy - capacity required to support the RAID 0/1 and RAID 5 storage techniques used by the disk array for data redundancy. This capacity is managed by the array controller and cannot be altered or reduced. This is the only portion of the array capacity that you cannot control. • Active Hot Spare - capacity reserved to perform a rebuild if a disk fails. The disk array creates an Active Hot Spare large enough to rebuild the largest disk in the array. Until needed, the array uses the Active Hot Spare capacity as RAID 0/1 space to improve performance. The capacity for the Active Hot Spare is distributed across all the disks in the array. • Unallocated - capacity that has not been allocated to a logical drive or the Active Hot Spare. The array uses unallocated capacity as RAID 0/1 storage to improve system performance. Should you need to increase capacity, you can use the unallocated capacity to create a new logical drive. • Disks Not In Use - capacity contained on any disk that is installed in the array enclosure but is not included in the array configuration. Such disks are not being currently used by the disk array to store any user data. 100 Concepts