Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

182 Creating and administering disk groups
Handling conflicting configuration copies
shared disk group, the actual serial IDs on the disks do not agree with the expected values
from the configuration copies on other disks in the disk group.
Depending on what happened to the different portions of the split disk group, there are two
possibilities for resolving inconsistencies between the configuration databases:
■ If the other disks in the disk group were not imported on another host, VxVM
resolves the conflicting values of the serial IDs by using the version of the
configuration database from the disk with the greatest value for the updated ID
(shown as update_tid in the output from the
vxdg list diskgroup command).
This case is illustrated below.
Figure 4-2 Example of a serial split brain condition that can be resolved
automatically
■ If the other disks were also imported on another host, no disk can be considered to
have a definitive copy of the configuration database. The figure below illustrates how
this condition can arise for two disks.
Disk A
Actual A = 1
Expected A = 1
Expected B = 0
Configuration
database
Disk B
Actual B = 0
Expected A = 0
Expected B = 0
Configuration
database
Imported shared disk group
Disk A
Actual A = 1
Expected A = 1
Expected B = 0
Configuration
database
Disk B
Actual B = 0
Expected A = 1
Expected B = 0
Configuration
database
Partial disk group
imported on host X
Disk B not imported
1.Disk A is imported on a separate
host. Disk B is not imported. The
actual and expected serial IDs are
updated only on disk A.
2.The disk group is re- imported on
the cluster. The configuration copy on
disk A is used to correct the
configuration copy on disk B as the
actual value of the updated ID on disk
A is greatest.