5.14.3. Performing Maintenance on an Entire Dataservice

To perform maintenance on all of the machines within a dataservice, a rolling sequence of maintenance must be performed carefully on each machine in a structured way. In brief, the sequence is as follows

Perform maintenance on each of the current slaves
Switch the master to one of the already maintained slaves
Perform maintenance on the old master (now in slave state)
Switch the old master back to be the master again

A more detailed sequence of steps, including the status of each datasource in the dataservice, and the commands to be performed, is shown in the table below. The table assumes a three-node dataservice (one master, two slaves), but the same principles can be applied to any master/slave dataservice:

Step	Description	Command	host1	host2	host3
1	Initial state		Master	Slave	Slave
2	Set maintenance policy	set policy maintenance	Master	Slave	Slave
3	Shun slave `host2`	datasource host2 shun	Master	Shunned	Slave
4	Perform maintenance		Master	Shunned	Slave
5	Validate the `host2` server configuration	tpm validate	Master	Shunned	Slave
6	Recover the slave `host2` back	datasource host2 recover	Master	Slave	Slave
7	Ensure the slave ( `host2` ) has caught up		Master	Slave	Slave
8	Shun slave `host3`	datasource host3 shun	Master	Slave	Shunned
9	Perform maintenance		Master	Slave	Shunned
10	Validate the `host3` server configuration	tpm validate	Master	Slave	Shunned
11	Recover slave `host3` back	datasource host3 recover	Master	Slave	Slave
12	Ensure the slave ( `host3` ) has caught up		Master	Slave	Slave
13	Switch master to `host2`	switch to host2	Slave	Master	Slave
14	Shun `host1`	datasource host1 shun	Shunned	Master	Slave
15	Perform maintenance		Shunned	Master	Slave
16	Validate the `host1` server configuration	tpm validate	Shunned	Master	Slave
17	Recover the slave `host1` back	datasource host1 recover	Slave	Master	Slave
18	Ensure the slave ( `host1` ) has caught up		Master	Slave	Slave
19	Switch master back to `host1`	switch to host1	Master	Slave	Slave
20	Set automatic policy	set policy automatic	Master	Slave	Slave

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5.14.2. Performing Maintenance on a Master	Home	5.14.4. Making Online Schema Changes