Upgrading Managed Servers
You can use the Rolling Pool Upgrade wizard to upgrade XenServer - standalone servers or a pool of servers to a newer version.
Note: The Rolling Pool Upgrade wizard is available for XenServer Enterprise Edition customers, or those who have access to XenServer through their Citrix Virtual Apps and Desktops entitlement. For more information, see About XenServer Licensing.
The Rolling Pool Upgrade wizard guides you through the upgrade procedure and organizes the upgrade path automatically. The Rolling Pool Upgrade wizard allows you to upgrade multiple servers and pools simultaneously. Each of the servers in the pool is upgraded in turn, starting with the pool master. Before starting an upgrade, the wizard conducts a series of prechecks to ensure that certain pool-wide features, such as HA and WLB, are temporarily disabled and that each host in the pool is prepared for upgrade (for example, that the CD/DVD drive of each host is empty). Only one server is offline at a time, and any running VMs are automatically migrated off each server before the upgrade is installed on that server.
The wizard can operate in manual or automatic mode:
- In manual mode, you must manually run XenServer installer on each server in turn and follow the on-screen instructions on the serial console of the server. When the upgrade begins, XenCenter prompts you to insert XenServer installation media or specify a PXE boot server for each server that you upgrade.
- In automatic mode, the wizard uses network installation files located on an HTTP, NFS or FTP server to upgrade each server in turn, without requiring you to insert install media, manually reboot, or step through the installer on each server. If you choose to perform a rolling pool upgrade in this manner, unpack the XenServer installation media onto your HTTP, NFS or FTP server before starting the upgrade.
You can also use the Rolling Pool Upgrade wizard to upgrade standalone server s, that is, server s which do not belong to any resource pool.
Important: Before you upgrade
Upgrading a pool of server s requires careful planning. As you plan your upgrade, it is very important to be aware of the following:
- Download and install the latest version of XenCenter. For example, when you are upgrading your hosts to XenServer 7.6, you must use XenCenter issued with XenServer 7.6. Using earlier versions of XenCenter to upgrade to a newer version of XenServer is not supported.
- VMs can only be migrated from a server running an older version of XenServer to one running the same version or higher. You cannot migrate VMs from an upgraded server to one running an older version of XenServer. Ensure to allow for space on your servers accordingly.
- Citrix strongly advises against running a mixed-mode pool (one with multiple versions of XenServer coexisting) for longer than necessary, as the pool operates in a degraded state during upgrade.
- Key control operations are not available during upgrade and should not be attempted. Though VMs continue to function as normal, VM actions other than migrate may not be available (for example, shut down, copy, and export). In particular, it is not safe to perform storage-related operations such as adding, removing or resizing virtual disks.
- The wizard will always upgrade the pool master first. Do not place the pool master into maintenance mode using XenCenter before performing the upgrade as this will cause a new master to be designated.
- Take a backup of the state of your existing pool using the pool-dump-database xe CLI command. For more information, see Command line interface. This allows you to revert a partially complete rolling upgrade back to its original state without losing any VM data. As it is not possible to migrate a VM from an upgraded server to a server running an older version of XenServer, it may be necessary to shut down VMs if you need to revert the rolling upgrade for any reason.
- Ensure that your servers are not over-provisioned - that is, they have sufficient memory to carry out the upgrade. It is best to suspend any VMs that are not critical during the upgrade process.
- While the Rolling Pool Upgrade wizard checks that the following actions have been taken, you may choose to perform them before you begin the upgrade:
To upgrade XenServer using the Rolling Pool Upgrade wizard
- Open the Rolling Pool Upgrade wizard: on the Tools menu, select Rolling Pool Upgrade.
- Read the Before You Start information, and then click Next to continue.
- Select the pool or standalone servers that you would like to upgrade and then click Next.
Choose the Upgrade Mode. You can select either Automatic Mode or Manual Mode depending on whether you are planning an automated upgrade from network installation files located on an HTTP, NFS or FTP server, or a manual upgrade from either a CD/DVD or a server via PXE boot.
Note: If you choose Manual Mode , you must run XenServer installer on each server in turn and follow the on-screen instructions on the serial console of the server. When the upgrade begins, XenCenter prompts you to insert XenServer installation media or specify a PXE boot server for each server that you upgrade.
- Choose whether you want XenCenter to automatically download and install the minimal set of updates (hotfixes) after upgrading the servers to a newer version. The apply updates option is selected by default. However, you must have internet connection to download and install the updates.
- After selecting the Upgrade Mode, click Run Prechecks.
- Follow the on-screen recommendations to resolve any upgrade prechecks that have failed. If you would like XenCenter to automatically resolve all failed prechecks, click Resolve All. When the prechecks have been resolved, click Next to continue.
Prepare the XenServer installation media:
- If you chose Automatic Mode , enter the installation media details. Choose HTTP , NFS or FTP and then specify the path, username and password, as appropriate.
- If you chose Manual Mode , note the upgrade plan and instructions.
Click Start Upgrade to begin the upgrade.
When the upgrade begins, the wizard guides you through any actions you need to take to upgrade each server. Follow the instructions until you have upgraded and updated all servers in the pool.
Note: If the upgrade or the update process fails for any reason, the Rolling Pool Upgrade wizard halts the process. This allows you to fix the issue and resume the upgrade process by clicking the Retry button.
The Rolling Pool Upgrade wizard prints a summary when the upgrade is complete. Click Finish to close the wizard.