Setting up majority quorum

You can add a dedicated host or a member to an existing cluster for setting up majority quorum in the cluster.

Before you begin

To perform this task, you must be a Db2® cluster services administrator.

Procedure

Add a member or tiebreaker host to the cluster to make the total number of hosts in the cluster odd.

Note: Before adding a dedicated tiebreaker host in both single site and geographically dispersed Db2 pureScale® cluster, follow procedure 4 in Getting the cluster installed and running in a GDPC environment
- Single site pureScale cluster
  1. Add a member host to make the total size odd by using the db2iupdt command.
    or
    Add a dedicated tiebreaker host with no access to user data to make the total size odd by using the following command:
```
db2cluster -add -host <TB hostname> -no_san_access
```
  2. Ensure that the new host was added to the RSCT and IBM Spectrum Scale clusters by using the following commands:
```
db2cluster -cm -list -host
db2cluster -cfs -list -host
```
- Geographically dispersed pureScale cluster (GDPC)
  1. For a GDPC with equal number of members and CFs in the primary and secondary sites, run the following command to add the dedicated tiebreaker host to the third site that has no access to the storage in redundancy groups 1 and 2:
```
db2cluster -add -host <TB hostname> -no_san_access
```
  2. Ensure that the new host was added to the RSCT and IBM Spectrum Scale clusters by using the following commands:
```
db2cluster -cm -list -host
db2cluster -cfs -list -host
```
Change the cluster manager quorum type to majority node set and verify.
- Query the current tiebreaker device by using the following command:
```
db2cluster -cm -list -tiebreaker
```
- If the output of the previous step does not specify ‘Majority Node Set’ as the quorum device, update as follows:
```
db2cluster -cm -set -tiebreaker –majority
```
- Verify the setting and compare it to the expected output.
```
db2cluster -cm -list -tiebreaker
The current quorum device is of type Majority Node Set.
```
Change the IBM Spectrum Scale quorum type for the cluster to majority node set and verify.
- Query the current tiebreaker device by using the following command:
```
db2cluster -cfs -list -tiebreaker
```
- If the output of the previous step does not specify ‘Majority Node Set’ as the quorum device, update as follows:
```
db2cluster -cfs -set -tiebreaker –majority
```
- Verify the setting and compare it to the expected output.
```
db2cluster -cfs -list -tiebreaker
The current quorum device is of type Majority Node Set.
```