IBM SG24-5131-00 用户手册

Cluster Management and Administration 

Changes to VG constructs are probably the most frequent kind of changes to 
be performed in a cluster. As a system administrator of an HACMP for AIX 
cluster, you may be called upon to perform any of the following LVM-related 
tasks:

  • Creating a new shared volume group

  • Extending, reducing, changing, or removing an existing volume group

  • Importing, mirroring, unmirroring, or synchronizing mirrors of a volume 

group

  • Creating a new shared logical volume

  • Extending, reducing, changing, copying, or removing an existing logical 

volume (or a copy)

  • Creating a new shared file system

  • Extending, changing, or removing an existing file system

The varyon of a shared volume group will only succeed if the information 
stored in the VGDA on the disks of the shared volume group and the 
information stored in the ODM are equal. After changes in the volume group 
(e. g. increasing the size of a file system), the information about the volume 
group in ODM and in the VGDA on the disks are still equal, but it will be 
different from the information in the ODM of a node that did not have the 
volume group varied on at the time of the change. In order to keep a takeover 
from failing, the volume group information must be synchronized. There are 
four distinct ways to keep all the volume group ODMs synchronized:

  • Manual Update

  • Lazy Update

  • C-SPOC

  • TaskGuide

Chapters 4 and 5 of the 

HACMP for AIX, Version 4.3: Administration Guide, 

SC23-4279, describe in detail how to change shared LVM components.

Sometimes, manual updates of shared LVM components are inevitable 
because you cannot do some of the tasks mentioned above with any of the 
tools. For example, neither with C-SPOC nor with TaskGuide or Lazy Update 
is it possible to remove a VG on all of the cluster nodes.