AIX - Quorum

The following commands change the quorum for the volume group testvg. This
Attribute determines if the volume group will be varied off or not after losing the
Simple majority of its physical volumes.

To turn off the quorum use the command:

#chvg -Qn testvg

To turn on the quorum use the command:

# chvg -Qy testvg

Quorum is used for data integrity. When we activate quorum in VG it will recover 51% of data in VG

If we have DATAVG, This DATAVG has two PV’s hdisk1, hdisk2.

First PV hdisk1 has 2 * VGDA and 1 *VGSA

Second PV hdisk2 has 1* VGDA and 1*VGSA

Each VGDA has 33% of data, so hdisk1 has 2 VGDA, it will protect 66% of data and Second PV hdisk2 has 1 VGDA, it will protect only 33% data.

AIX - Quorum - LVCB (Logical Volume control block)

AIX - Quorum - LVCB (Logical Volume control block)

LVCB (Logical Volume control block)

Logical volume control block (LVCB) contains important information about the
Logical volume, such as the number of the logical partitions or disk allocation
Policy. Its architecture and location on the disk depends on the type of the
Volume group it belongs to. For standard volume groups, the LVCB resides on
The first block of user data within the LV. For big volume groups there is
Additional LVCB information in VGDA on the disk. For scalable volume groups
All relevant logical volume control information is kept in the VGDA as part of
The LVCB information area and the LV entry area.

AIX - Quorum - VGSA (Volume Group Status Area)

VGSA (Volume Group Status Area)

Volume group status area (VGSA) is used to describe the state of all physical
Partitions from all physical volumes within a volume group. The VGSA
indicates if a physical partition contains accurate or stale information. VGSA
Is used for monitoring and maintained data copies synchronization. The
VGSA is essentially a bitmap and its architecture and location on the disk
Depends on the type of the volume group.

AIX - Quorum - VGDA (Volume Group Descriptor Area)

AIX - Quorum - VGDA (Volume Group Descriptor Area)

Volume group descriptor area (VGDA) is an area on the disk that contains
Information pertinent to the volume group that physical volume belongs to. It
Also includes information about properties and status of all physical and
Logical volumes that are part of the volume group. The information from VGDA
is used and updated by LVM commands. There is at least one VGDA per
Physical volume. Information from VGDAs of all disks that are part of the
Same volume group must de identical. VGDA internal architecture and location on the disk depends on the type of the volume group (original, big, or
Scalable).

AIX - Quorum

-VGDA
-VGSA
-LVCB

AIX - LVM - Change Volume Group

Using chvg command we can change the VG options

#chvg –a y datavg (datavg is automatically activated at startup)
#chvg -a n datavg (To deactivate the automatic activation at startup)
#chvg –t 2 datavg (To change max. no of PP to 2032 on vg datavg)
#chvg –Qn datavg (To disable quorum on VG datavg)
#chvg –Qy datavg (To activate quorum on VG datavg)
#chvg –u datavg (To unlock the VG)

AIX - LVM - Import Volume Group

AIX - LVM - Import Volume Group

Using importvg command we can import the DATAVG to ServerB

First you should connect hdisk3, hdisk4, in ServerB then, run the
#cfgmgr (for hard disk detection)

Then check the PV’s installed or not using lspv command
#lspv (it will display the installed PV’s) if hdisk3, hdisk4 is available then PV’s are configured properly.

Then run the command importvg for import the DATAVG

#importvg –y DATAVG hdisk3 (VG information is added in ODM)
#importvg –y DATAVG hdisk4 (VG information is added in ODM)

NOTE:

If ServerB has VG with same name DATAVG, This case we can rename the importing VG DATAVG to other name,

#importvg –y NEWDATAVG hdisk3
#importvg –y NEWDATAVG hdisk4

Like this we can import.

After importing the DATAVG, we no need to Varryon DATAVG, automatically it will Varryon while importing.

AIX - LVM - Export Volume Group

AIX - LVM - Export Volume Group

Using exportvg command we can export VG (including all the PV’s) from one server to another server.

If you have ServerA, in this server has DATAVG with two PV’s. Now we want export DATAVG to ServerB

Before exporting the DATAVG, we should Varryoff the DATAVG, i.e. DATAVG is moved to offline.

#varryoff DATAVG (Varryoff the DATAVG)
#exportvg DATAVG (VG information removed from ODM)

Now DATAVG is exported from the ServerA, after this run the following command to verify the export.

#lsvg

It won’t show DATAVG name. Because DATAVG is exported.

Then you should remove PV from the configuration

#rmdev –dl hdisk3
#rmdev –dl hdisk4

After that we can remove the PV’s from ServerA for import DATAVG to ServerB.

AIX - LVM - Migrate Logical Volume

AIX - LVM - Migrate Logical Volume

Using migratepv command we can migrate lv from PV to PV

If we want to migrate single LV

#migratepv –l testlv hdisk1 hdisk2

After executing above command testlv LV is moved hdisk2.

AIX - LVM - Migrate Physical Volume

AIX - LVM - Migrate Physical Volume

Using migratepv command we can move full PV data or single LV from one PV to another PV. This is not copy just cut and past method

If we want to migrate data from PV to PV

#migratepv hdisk1 hdisk2

After executing above command hdisk1 data is moved to hdisk2.