The GLSB upgrade process includes setting up the GSLB sites in the maintenance mode.

In the maintenance mode, configuration changes are not allowed. The health check polling is set to high value, say 1800 second, that make federation on low entropy.

You can upgrade the active follower site using the maintenance mode.

Pre-upgrade Steps for GSLB Leader Site

The maintenance mode is global setting and can be set from leader site.

In maintenance mode, the configuration changes cannot be performed at any GSLB sites. For any new configuration, all the sites have to wait for the completion of the upgrade process. The maintenance mode is a global setting. It gets applied to all the GSLB sites and is not local to only one of them.

Maintenance Mode

For upgrading the leader site, only the maintenance mode is available. In maintenance mode, the configuration changes cannot be performed at any of the GSLB sites. The new configuration can only be done after disabling maintenance mode.

The maintenance mode is a global setting, it gets applied to all across the GSLB sites, and it is not local to only one of the sites.

Note:

You need to enable maintenance mode on the GSLB leader Controller before starting the upgrade on the leader to prevent issues.

Enabling Maintenance Mode

On the GSLB leader, enable GSLB maintenance mode using the REST API or the following CLI command:

gslb maintenancemode enabled

As a result, Avi Load Balancer takes the following steps:

  • GSLB configuration changes are blocked. We do not want any GSLB configuration changes applied at the leader site while follower sites are upgraded.

  • Health-monitor probe frequency is reduced by changing the send_interval to 30 minutes.

  • The cached states of remote sites are not flushed for time T, according to the calculation:

    T = gslb_cfg.send_interval x gslb_cfg.clear_on_max_retries

    The remote site is not declared down during this interval.

Upgrading the GSLB Sites

Upgrade the site to the new version of Avi Load Balancer. Depending on the number of virtual services, configuration, and so on, this might take anywhere between 15 and 45 minutes for the entire site (Controllers and SEs) to be upgraded. Followers are upgraded first and the leader is the last to be upgraded.

Upgrade status can be checked using the CLI command show upgrade status.

Post-upgrade

  1. For using maintenance mode as the pre-upgrade step, you need to disable GSLB maintenance mode on the leader site using the CLI command gslb no maintenancemode. After performing this step, the newly upgraded remote site can build its runtime states from the rest of the GSLB ecosystem.

  2. The new recommendation is to always disable and re-enable maintenance mode for status across to converge.

Repeat the pre-upgrade, upgrade and post-upgrade steps for all followers and finally for the leader.

Note:

After all the sites have been upgraded, Ansible modules must be migrated to the latest version.