E.2. Metadata Contents

The volume group metadata contains:
  • Information about how and when it was created
  • Information about the volume group
The volume group information contains:
  • Name and unique id
  • A version number which is incremented whenever the metadata gets updated
  • Any properties, such as: read/write or resizable
  • Any administrative limit on the number of physical volumes and logical volumes it may contain
  • The extent size (in units of sectors which are defined as 512 bytes)
  • An unordered list of physical volumes making up the volume group, each with:
    • Its UUID, used to determine the block device containing it
    • Any properties, such as whether the physical volume is allocatable
    • The offset to the start of the first extent within the physical volume (in sectors)
    • The number of extents
  • An unordered list of logical volumes, each consisting of
    • An ordered list of logical volume segments. For each segment the metadata includes a mapping applied to an ordered list of physical volume segments or logical volume segments