What is vgda?

[Hill_1]

1. I would like to know what is vgda?
2. What is the function of it?
3. When we need the vgda?

Thanks.

[Michael Tully]

Hi,

Have a look at the attached link, it is explains it well.

http://forums.itrc.hp.com/cm/QuestionAnswer/1,1150,0x57cb996c5988d5118ff10090279cd0f9,00.html

[linuxfan · Accepted solution]

Hi,

1 VGDA stands for
Volume Group Description Area

2. what is its function?
It contains information on the Volume Group(VG) to which the physical volume(PV) belongs, it has information about how many Logical Volumes(LV) are in this VG, how many physical volumes(disks) make up this Volume Group etc

3. when do we need VGDA
If you are using LVM (Logical Volume Manager) to manage your disks on the system.

For more information as to how LVM works look at chapter 6 (Managing Disks and File Systems)
http://docs.hp.com/hpux/pdf/B2355-90742.pdf

-Hope that helps
I am RU

[A. Clay Stephenson]

Hi,

In addition to storing the number of Physical Volumes in this Volume Group and the number of Logical Volumes in this Volume Group, the VGDA also contains the Logical Extent -> Physical Extent Map for each Logical Volume in this Volume Group.

The main function of this map is to tell the OS that, for example, Lvol1's logical block 54 physically resides at block 6934 of /dev/dsk/c1t5d0.

Clay