Dell 6 series User Manual page 150

The Dell OpenManage™ storage management application configures the disks
after you have installed the operating system. Storage Management enables you
to perform controller and enclosure functions for all supported RAID and
non-RAID controllers and enclosures from a single graphical or command-line
interface without requiring the use of the controller BIOS utilities.
SAS RAID Storage Manager configures, monitors, and maintains the PERC 6
controllers, battery backup units, and other devices running on a system.
Read-Ahead
A memory caching capability in some controllers that allows them to read
sequentially ahead of requested data and store the additional data in cache
memory, anticipating that the additional data is required soon. Read-Ahead
supplies sequential data faster, but is not as effective when accessing random data.
Rebuild
The regeneration of all data to a replacement disk in a redundant virtual disk
(RAID level 1, 5, 6, 10, 50, or 60) after a physical disk failure. A disk rebuild
normally occurs without interrupting normal operations on the affected virtual
disk, though some degradation of performance of the disk subsystem can occur.
Rebuild Rate
The percentage of central processing unit (CPU) resources devoted to
rebuilding. 100% rebuild rate does not mean ALL CPU resources will be
dedicated to the rebuild without processing IOs.
Reconstruct
The act of remaking a virtual disk after changing RAID levels or adding a
physical disk to an existing virtual disk.
Redundancy
The provision of multiple interchangeable components to perform a single
function to cope with failures and errors. Common forms of hardware redundancy
are disk mirroring, implementations of parity disks, or distributed parity.
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Glossary