HP Serviceguard manual Summary, Comparison of Different Arbitration Methods

Arbitration for Data Integrity in Serviceguard Clusters

Summary

Summary

This paper has described a number of approaches to arbitration to provide safety for data in high availability clusters. There are advantages and disadvantages to each of the major approaches using a lock disk, a quorum server, or arbitrator nodes.

Table 1	Comparison of Different Arbitration Methods
Arbitration	Advantages	Disadvantages
Mode
Lock Disk	• Does not require a	• Requires separate disk hardware
	separate system.	that must be cabled to all nodes.
	• Disk can be used for	• Can only be used with clusters up
	other purposes as well.	to 4 nodes.
	• Legacy method that has	• Not available on Linux.
	been used for many	• Acquiring the lock follows an
	years.
		arbitration protocol, and this adds
		to failover time.
		• Use in extended distance clusters
		requires dual lock disks, with a
		slight risk of split brain.
Lock LUN	• Does not require a	• Requires separate disk hardware
	separate system.	that must be cabled to all nodes.
	• Disk can be used for	• Can only be used with clusters up
	other purposes as well.	to 4 nodes.
	• Similar to HP-UX lock	• Acquiring the lock follows an
	disk.	arbitration protocol, and this adds
		to failover time.
		• Dual lock LUNs are not
		supported, including extended
		clusters.

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