Volume Group Descriptor Area (VGDA)

Information about all the LVs and PVs within a VG. The first 64K of a PV is reserved for this area – defined in <sys/bootrecord.h>.

The VGDA consists of

  • BOOTRECORD: – first 512 bytes. Allows the Read Only System (ROS) to boot system
  • BAD BLK DIRECTORY – found in <sys/bddir.h>
  • LVM RECORD – found in <lvmrec.h>

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Volume Group Characteristics

You can find below the meaning of each parameter on Volume Group Characteristics (the output from lsvg vg command):

 

  1. Volume Group: Name of Volume Group.
  2. VG State: active/partial. Partial indicates that some of the Physical Volumes in the Volume Group are not active.
  3. VG Permission: It indicates if the volume group is read-only or read-write.
  4. Max LVs: Maximum number of Logical Volumes allowed in Volume Group.
  5. LVs: Total number of Logical Volumes at present in Volume Group.
  6. Open LVs: Number of LVs open at present in the Volume Group for any Read Write operation.
  7. Total PVs: Total number of Physical Volumes present in Volume Group.
  8. Stale PVs: How many stale Physical Volumes are there in Volume Group. The stale Physical Volumes are those ones on which I/O operations are not possible.
  9. Active PVs: Total number of Physical Volumes which are active in Volume Group.
  10. Max PPs per VG: Maximum no. of Physical Partitions which can be there in the Volume Group.
  11. Max PPs per PV: Maximum number of Physical Partitions which can be there in Physical Volume.
  12. VG Identifier: The very long string to identify Volume Group.
  13. PP Size: The size of Physical Partition used in every Physical Volume of Volume Group.
  14. Total PPs: Total number of Physical Partitions in Volume Group.
  15. Free PPs: Total number of free Physical Partitions with in Volume Group.
  16. Used PPs: Total number of Physical Partitions in use in Volume Group.
  17. Quorum: Whether the quorum is on or not in Volume Group.
  18. VG Descriptors: Number of Volume Group Descriptor Areas(VGDA) in Volume Group.
  19. Stale PPs: How many Physical Partitions are stale or unable to perform I/O operations.
  20. Auto On: Whether the Volume Group will varyon on system startup or not.
  21. Max PVs: Maximum number of Physical Volumes allowed in this Volume Group.
  22. Auto Sync: Whether this Volume Group should sync automatically or not.
  23. BB Policy: Its bad block relocation policy. So, this value here is relocatable, that means we are allowed to relocate bad blocks in this Volume Group if need be.

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OLAP

OLAP (online analytical processing): is computer processing that enables a user to easily and selectively extract and view data from different points of view.

For example, a user can request that data be analyzed to display a spreadsheet showing all of a company’s beach ball products sold in Florida in the month of July, compare revenue figures with those for the same products in September, and then see a comparison of other product sales in Florida in the same time period.

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