The order you upgrade the sites (protected or recovery) is not relevant, as long as paired sites remain only one major version apart.
You can upgrade from version N to the following version (N+1) of Zerto Virtual Replication (including any update within the current version). One cannot do an N+2 upgrade directly. For example, upgrade is supported for Zerto version 5.0Ux to 5.5Ux.
If you need to upgrade more than one version higher, you may either upgrade one version at a time, or uninstall the old version of Zerto Virtual Replication and install the new version. Please be sure to use the Zerto Diagnostics utility’s export option to export the existing VPG definitions before uninstalling.
For more information regarding the version you can upgrade to (based on your current version), in addition to the required steps, please review the ‘Guidelines to Upgrading Zerto Virtual Replication’ section in our ZVM Online Help.
To access the ZVM Online Help, click https://www.zerto.com/myzerto/technical-documentation/ and open the HTML file for the relevant platform.
Before upgrading, please verify the following:
1. A Zerto Virtual Manager can be used with a different version on another site, as long as the other version is only one version higher or lower.
2. Before upgrading, make sure that all VPGs are in protecting state and not in a sync state, such as Delta Sync, or an error state, such as Needs Configuration.
3. Complete any recovery operation before starting the upgrade.
4. When upgrading, the protection of the virtual machines continues, but during the upgrade no new checkpoints are written to the journal, resulting in alerts after the upgrade, even if only one of the sites was upgraded. After the upgrade, Zerto alerts might be issued stating that the journal history and RPO do not meet the specified targets.
5. When upgrading Zerto Virtual Replication PowerShell cmdlets, make sure that Windows PowerShell is closed before installing the new version.
When upgrading Zerto Virtual Replication, the VRAs that were installed in the previous version are not upgraded automatically. Therefore, the next step would be to upgrade the VRAs. To do so, upon completing the upgrade of both ZVMs, please follow the steps stipulated in the section ‘Upgrading VRAs’, in the ZVM Online Help.
Unlike the ZVR upgrade, upgrading VRAs will have an impact on replication. When upgrading source VRAs (VRAs that are currently managing protected virtual machines), you can minimize replication downtime by vMotion the protected virtual machines managed by the VRA to another host, on the same site, with a VRA.
If you choose to upgrade the VRA without vMotioning the virtual machines, a Delta Sync is performed following the upgrade. Upgrading a target VRA (a VRA that manages recovery of virtual machines) results in a Bitmap Sync being performed after the upgrade. The time to upgrade a VRA is short, so the Bitmap Sync should be quick.
For CSPs - ZCM:
When using the Zerto Cloud Manager, you must upgrade the Zerto Cloud Manager to be consistent with the latest version of Zerto Virtual Replication run by the CSP. Upgrade Zerto Virtual Replication and Zerto Cloud Manager in parallel. First upgrade Zerto Cloud Manager and then upgrade Zerto Virtual Replication so that they are never more than one version apart.
Zerto Cloud Connectors (ZCC) do not require upgrading when a new Zerto Virtual Replication version is released.