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LVM Working Theorem

When LVM prepares to store data into one LV, how does it determine which real disk(s) it should choose? In LVM, one PV comprises several PEs (Physical Extents) and one LV comprises several LEs (Logical Extents). These PEs map LEs directly and their translating relation is stored into a 'PE/LE Translation Table' (situated in VGDA). Stored in LVM disk, Translation Table will be loaded to internal memory as soon as VG is activated. PE is appointed when creating VG with 4M default size; Whether or not the size and type of the real hard disk are the same, all PEs are as big as each other in one VG. LV being created, LVM system creates LE with automatically maintenance of PE/LE Translation Table so that each LE in LV can find its mapping PE. In conclusion, LVM system knows where to write down disk data.


Previous: Logical Relationship among Disk Partition, Volume Group, Logical Volume and the File System Up: Next: How to Use RFLVM (Red Flag LVM Manager)