VCS: PanicSystemOnDGLoss

This is a configurable option that is on by default in the 5.0 version of VCS. If a disk group becomes completely invisible to a VCS node PanicSystemOnDGLoss option will panic the system immediately; the idea being it will improve recovery time as the service groups will start failing over to the remote side faster.

The down side - on extremely busy cluster nodes the DG agent can fail to complete in the allotted time and triger this option; which is how I learned about it. So, In the event that a cluster node appears to crash for seemingly no reason check the following URL for details.

To check if the VCS option is turned on, run the following command (1 is enabled, 0 is disabled):

# grep "boolean Panic" /etc/VRTSvcs/conf/config/types.cf

boolean PanicSystemOnDGLoss = 0

How to change the default value for PanicSystemOnDGLoss:

# haconf -makerw
# haattr -default DiskGroup PanicSystemOnDGLoss 0
# haconf -dump -makero

Confirm that both the temporary and persistent definitions have been reset to 0:

# haattr -display DiskGroup |grep Panic
PanicSystemOnDGLoss [boolean/scalar] = 0

# grep "boolean Panic" /etc/VRTSvcs/conf/config/types.cf
boolean PanicSystemOnDGLoss = 0


How to change the value for this attribute for individual DiskGroup resources:
In certain cases, it may be necessary to change this attribute to 1 for few selected DiskGroup resources.

# haconf -makerw
# hares -display DG_Res1 | grep PanicSystemOnDGLoss
DG_Res1 PanicSystemOnDGLoss global 0
# hares -modify DG_Res1 PanicSystemOnDGLoss 1
# hares -display DG_Res1 | grep PanicSystemOnDGLoss
DG_Res1 PanicSystemOnDGLoss global 1
# haconf -dump -makero