V11 SP8
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Deployment Scenarios for Citrix Xen

Deployments for Citrix Xen require the following objects:

  • At least one Virtual Server Agent (VSA) must be installed on a dedicated virtual machine on a XenServer. You must have at least one VSA proxy in each Xen pool. The first proxy added to the Xen instance coordinates backup operations across all proxies for the Xen pool.
    • A single VSA proxy can support all XenServers that use the same shared storage repository.  Each proxy can back up VMs in the same Xen pool that reside on a shared storage repository. For VMs on local storage, a proxy that has access to the local storage is required.

      If the first proxy does not have direct access to all virtual machine storage repositories (SRs) to be backed up, identify additional proxies on XenServers that have direct access to the storage repositories. If storage repositories are shared across all XenServers, additional proxies are not required.

    • To provide greater capacity and load balancing for virtual machines hosted on a XenServer, install additional VSA proxies on the XenServer. Multiple proxies can distribute the workload and perform backups more quickly.
    • If one of the other proxies becomes unavailable, any VSA proxy in the Xen pool can continue to provide backup and restore services.
  • A virtualization client must be configured for each Xen pool. The virtualization client connects to the master XenServer in the pool.

Simple Deployment: Single Xen Pool

In a simple deployment, a single Xen pool supports a small number of VMs with two XenServers. Both XenServers access the same shared storage repository.

Following best practice, install the Virtual Server Agent on a virtual machine for each XenServer.

  • Set up this deployment by creating a single Xen virtualization client for the Xen pool. The virtualization client is configured to connect to the master XenServer in the pool.
  • Add a VM on the first XenServer (for example, Xen Server 1) as the first proxy on the virtualization client, with the VSA proxy for the second XenServer added as an additional proxy.
  • Either VSA proxy can manage backups and restores for all VMs in the Xen pool because they all use the same shared storage.

Complex Deployment: Multiple Xen Pools with Shared and Local Storage

In a more complex deployment, multiple Xen pools support a large number of virtual machines.

In this example, some storage repositories are shared by two or more XenServers, and one XenServer uses local storage.

This deployment requires at least two Xen virtualization clients (one for each Xen pool):

  • XenPool A
    • Virtualization client A has VSA proxies for XenServers 1-4. The virtualization client connects to the master XenServer (1).
    • A VM on the first XenServer (XenServer 1) is the first proxy added; the VSA proxies for XenServers 2-4 are added as additional proxies.
    • If one of the VSA proxies for XenServers 1 or 2 goes offline, the other proxy can handle the workload for virtual machines on the first shared storage repository.
    • If one of the VSA proxies for XenServers 3 or 4 goes offline, the other proxy can handle the workload for virtual machines on the second shared storage repository.
  • XenPool B
    • Virtualization client B has VSA proxies for XenServers 5-7. The virtualization client connects to the master XenServer (5).
    • A VM on the first XenServer (XenServer 5) is the first proxy added; the VSA proxies for XenServers 6-7 are added as additional proxies.
    • XenServers 5 and 6 have two VSA proxies each to provide load balancing for VM backups for each host. In addition, if both proxies on one of the hosts go offline, the proxies on the other host can handle backups for VMs on the same shared storage.
    • Because XenServer 7 uses local storage, the VSA proxy for that server is the only proxy that can manage backups and restores for VMs on that server.

Disaster Recovery

In a disaster recovery scenario, you might need to recover virtual machines, storage repositories, or XenServer hosts.

  • Virtual machines can be recovered from backups performed by Commvault software.

    If storage repositories and XenServers are still available, you do not need to take any other actions.

  • Virtual machines can be restored in place if storage repositories have the same names as the original storage repositories for the VMs. If storage repositories with the original names are not available, you can browse and restore to different storage repositories.

  • If the original XenServer host is unavailable, you must rebuild the physical server by reinstalling the XenServer software and related updates. See XenServer documentation for details.