A Split-Brain Occurred During a Disk Scan

Publication Date:  2012-07-19 Views:  510 Downloads:  0
Issue Description

The error message "VxVM vxdg ERROR V-5-1-10127: Serial Split Brain detected. Use -ooverridessb to reattach the disk/site" is displayed when you scan disks on the ISM interface. The restored mirror disk cannot join the original disk group to restore the mirror, but the services are not affected.

Alarm Information
None
Handling Process

1. Run the vxplex -g diskgroup -f dis plex_name, vxedit -g diskgroup -rf rm plex_name, vxdg -g diskgroup rmdisk plex_name commands to separate and delete the mirror disk from the disk group.
For example, run the vxprint -g diskgroup command to view the information about the disk group, and the information shown in Figure 1 is displayed.
Figure 1 Viewing information about the disk group mirdg 
 
In the disk group mirdg, the mirror volume is mir_vol, the source disk is huawei-s5500-0_2, and the mirror disk is huawei-s5500-0_9.
a. Run the vxplex -g mirdg -f dis mir_vol–02 command to separate the plex mir_vol-02, which corresponds to the mirror disk.
b. Run the vxedit -g mirdg -rf rm mir_vol–02 command to delete the separated plex mir_vol-02.
c. Run the vxdg -g mirdg rmdisk huawei-s5500-0_9 command to separate the mirror disk from the disk group.
2. Run the vxdiskunsetup –C disk_name command to uninitialize the separated disk.
For example, after uninitializing the disk huawei-s5500-0_9, run the vxdisk list command to view the result, and the information shown in Figure 2 is displayed.
Figure 2 Viewing disk information 
 
After the uninitialization, the state of huawei-s5500-0_9 becomes online invalid.
3. Run the vxdiskunsetup –if disk_name command to initialize the separated disk.
For example, after initializing the disk huawei-s5500-0_9, run the vxdisk list command to view the result, and the information shown in Figure 3 is displayed.
Figure 3 Viewing disk information 
 
After the initialization, the state of huawei-s5500-0_9 becomes online.
4. Run the vxdg –g disk_name adddisk disk_name command to add the initialized disk to the disk group again.
For example, after adding the initialized disk huawei-s5500-0_9 to the disk group mirdg again, run the vxprint –g disk_name command to view the result, and information shown in Figure 4 is displayed.
Figure 4 Viewing information about the disk group mirdg 
 
5. Run the vxassist –g diskgroup mirror srl_vol alloc=disk_name command to add a mirror for the source volume again.
For example, add mirror to the original mirror volume mir_vol in the disk group mirdg, and select huawei-s5500-0_9 as the mirror disk. Then run the vxprint –g disk_name command to view the result, and information shown in Figure 5 is displayed.
Figure 5 Viewing information about the disk group mirdg 
 

Root Cause

The previously described phenomenon is called a disk split-brain.

The cause of a disk split-brain: Since operations are performed on the VIS6000 for configuration when an error (for example, an exceptional power-off or RAID group failure) occurs on the mirror array, IDs of disks in the disk group become inconsistent, as a result, VxVM cannot automatically import the disks. When you scan disks on the ISM after the array recovers, the system displays an error message.

Suggestions
None

END