Grain Directories and Grain Tables

SPARSE type virtual disks use a hierarchical representation to organize sectors. See Virtual Disk Format 5.0 referenced in Virtual Disk Internal Format. In this context, grain means granular unit of data, larger than a sector. The hierarchy includes:

• Grain directory (and redundant grain directory) whose entries point to grain tables.
  • Grain tables (and redundant grain tables) whose entries point to grains.
    • Each grain is a block of sectors containing virtual disk data. Default size is 128 sectors or 64KB.