The GLSB upgrade process includes setting up the GSLB sites in the maintenance mode. In the maintenance mode, none of the GSLB sites can participate in the GSLB process and configuration changes are not allowed on any of the GSLB sites.

The following are the two modes available for the upgrade of the active follower site. Enable one of these modes before starting the upgrade process:

  • Maintenance Mode.

  • Suspended Mode - This is available only for the active follower site.

Pre-upgrade Steps for GSLB Leader Site

For upgrading the leader site, only the maintenance mode is available.

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.

For more information, see Enabling Suspend Mode.

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. 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 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, NSX Advanced 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 NSX Advanced 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. If the suspended mode is selected for the follower site prior to upgrading it, enable the no suspended-mode for that specific follower site.

  2. If maintenance mode is used as the pre-upgrade step, disable GSLB maintenance mode on the leader site using the CLI command gslb no maintenance mode. After performing this step, the newly upgraded remote site can build its runtime states from the rest of the GSLB ecosystem.

  3. If you are ready to upgrade the next site, you can skip the Post-upgrade steps.

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.

Suspended Mode

In the suspended mode, configuration changes are prohibited only on the follower sites participating in the upgrade or maintenance activity. The other sites (the leader sites and the remaining follower sites) still participate in the GSLB process.

In suspended mode, the GSLB leader sites accept the configuration. The configuration changes are synchronized to all the follower sites except the one on which the suspended mode is enabled. If an error or incorrect configuration occurs, it is localized to the specific site only. The errors or crash issues do not get propagated to the other sites, and do not affect the application hosted through GSLB. The application is accessible while the upgrade or maintenance work continues on one of the active follower sites.

In suspended mode, configuration on the GSLB leader is not prohibited and it can have all the create, read, update, and delete (CRUD) operations. After the upgrade, once the follower site is set to no suspended mode, the follower will receive all the configuration from the leader site.

Note:

  • It is applicable to the follower site only. It cannot be applied to the leader site.

  • All configuration sync is performed once the site exits the suspended mode.

  • After the upgrade, the one-time configuration synchronization is performed between the follower sites and the leader site.