1.  Field
Embodiments of the invention relate to spare device management. 
2.  Description of the Related Art
A Redundant Array of Independent Disks (RAID) array may be described as a set of hard disk devices, and the set of hard disk devices provide fault tolerance and performance.  A RAID storage system may be described as one that uses RAID arrays.  RAID storage systems implement data storage by presenting logical disk devices that are logical entities constructed of multiple hard disk devices.  To enhance the availability and reliability characteristics of RAID arrays, RAID technology provides the capability to provide extra hard disk devices to act as “spare” device (i.e., spare hard disk devices) replacements for hard disk device failures.  With storage systems that are comprised of multiple RAID arrays, the capability for a single hard disk device to act as a spare device for multiple RAID arrays is known as global sparing. 
Some RAID storage systems may define spare devices at the time of RAID array creation.  When this type of implementation is used, specific spare devices are defined with a known set of characteristics and attributes.  In other RAID storage systems, default rules are created to define the number of spare devices required, and these RAID storage systems automatically select spare devices based on some set of criteria. 
In RAID storage systems that use spare assignment optimization techniques, it is not possible to define specific characteristics to ensure adequate performance attributes during failure of hard disk devices and/or repair of hard disk devices. 
Although RAID storage systems are useful, there is a need in the art for improved spare device management.