HP Veritas Volume Manager 5.0 -UX 11i v3 manual Automatically, Expected a = Expected B =

192Creating and administering disk groups

Handling conflicting configuration copies

for the disks in their copies of the configuration database, and also in each disk’s private region, are updated separately on that host. When the disks are subsequently re-imported into the original 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 the value of update_tid in the output from the vxprint -m diskgroup grep update_tid command). This case is illustrated below.

Figure 4-2	Example of a serial split brain condition that can be resolved
	automatically

Partial disk group

imported on host X

Disk A

Actual A = 1

Configuration

database

Expected A = 1

Expected B = 0

Disk B not imported

Disk B

Actual B = 0

Configuration

database

Expected A = 0

Expected B = 0

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.

Imported shared disk group
Disk A	Disk B
Actual A = 1	Actual B = 0
Configuration	Configuration
database	database
Expected A = 1	Expected A = 1
Expected B = 0	Expected B = 0

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.