Subelements Mapping is a link between element & next elements in I/O mapping stack

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• Nirja Shah   -Posted on 25 Sep 15
  - The mapping structures and the Oracle Database representation of these structures are described in this section.
  
  - You will need to understand this information in order to interpret the information in the mapping views.
  
  - The following are the primary structures that compose the mapping information:
  
  1. Files
  - A file mapping structure provides a set of attributes for a file, including file size, number of file system extents that the file is composed of, and the file type.
  
  2. File system extents
  - A file system extent mapping structure describes a contiguous chunk of blocks residing on one element.
  - This includes the device offset, the extent size, the file offset, the type (data or parity), and the name of the element where the extent resides.
  
  3. Elements
  - An element mapping structure is the abstract mapping structure that describes a storage component within the I/O stack.
  - Elements may be mirrors, stripes, partitions, RAID5, concatenated elements, and disks.
  - These structures are the mapping building blocks.
  
  4. Subelements
  - A subelement mapping structure describes the link between an element and the next elements in the I/O mapping stack.
  - This structure contains the subelement number, size, the element name where the subelement exists, and the element offset.

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