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193Creating and administering disk groups
Handling conflicting configuration copies
■ 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.
Figure 4-3 Example of a true serial split brain condition that cannot be resolved
automatically
This is a true serial split brain condition, which VxVM cannot correct
automatically. In this case, the disk group import fails, and the
vxdg utility
outputs error messages similar to the following before exiting:
VxVM vxconfigd NOTICE V-5-0-33 Split Brain. da id is 0.1, while
dm id is 0.0 for DM mydg01
VxVM vxdg ERROR V-5-1-587 Disk group newdg: import failed:
Serial Split Brain detected. Run vxsplitlines
The import does not succeed even if you specify the -f flag to vxdg.
Although it is usually possible to resolve this conflict by choosing the
version of the configuration database with the highest valued configuration
ID (shown as the value of
seqno in the output from the vxdg list diskgroup
| grep config
command), this may not be the correct thing to do in all
circumstances.
Disk A
Actual A = 1
Expected A = 1
Expected B = 0
Configuration
database
Disk B
Actual B = 1
Expected A = 0
Expected B = 1
Configuration
database
Shared disk group fails to import
Disk A
Actual A = 1
Expected A = 1
Expected B = 0
Configuration
database
Disk B
Actual B = 1
Expected A = 0
Expected B = 1
Configuration
database
Partial disk group
imported on host X
Partial disk group
imported on host Y
1.Disks A and B are imported
independently on separate hosts.
The actual and expected serial IDs
are updated independently on
each disk.
2.The disk group cannot be
reimported on the cluster. This is
because the databases do not
agree on the actual and expected
serial IDs. You must choose which
configuration database to use.