Arbitration For Data Integrity in Serviceguard Clusters, July 2007

Arbitration for Data Integrity in Serviceguard Clusters

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

Mode

Advantages Disadvantages

Lock Disk • Does not require a

separate system.

• Disk can be used for

other purposes as well.

• Legacy method that has

been used for many

years.

• Requires separate disk hardware

that must be cabled to all nodes.

• Can only be used with clusters up

to 4 nodes.

• Not available on Linux.

• Acquiring the lock follows an

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

separate system.

• Disk can be used for

other purposes as well.

• Similar to HP-UX lock

disk.