Provisioning server failover
All Citrix Provisioning servers within a site that can access a virtual disk provide the disk to target devices. On shared storage, multiple servers access the same physical files, allowing a target device to establish a connection on an alternate server.
This failover permits a connection to the active server if the connection is interrupted for any reason. When failover occurs, a target device does not experience any disruption in service or loss of data.
If a server failover occurs, only those servers with access to an identical replicated virtual disk provide that virtual disk to target devices. For example, if a virtual disk is replicated across three servers and one of the them is updated, that virtual disk is no longer identical. It is not considered if a server failover occurs. Even if the same exact update is made to two of the virtual disks, the timestamps on each differ, resulting in disks that are no longer identical.
Citrix Provisioning does not support virtual disk high availability on local storage in Private Image mode or vDisks that are currently in maintenance mode.
If load balancing is enabled and a server providing that virtual disk fails, the load is automatically balanced between the target device and the remaining servers. When load balancing is not enabled, a single server is assigned, providing the virtual disk to target devices. In such situations failover does not occur.
For information on automatically balancing the target device load between servers, see Managing Servers.
The server accessed by the target device does not necessarily become the one that accesses the virtual disk. Once connected, if one or more servers can access the virtual disk for this target device, the server that is least busy is selected.
To force all target devices to connect to a different server, stop the Stream Service on that server. Upon shutdown, the Stream Service notifies each target device to relogin to another server.
Testing target device failover
To ensure that devices can failover successfully, complete the following:
- Double-click the vDisk status icon on the target device; note the IP address of the connected Citrix Provisioning server.
- Right-click the connected server in the Citrix Provisioning console. Select Stream Services, then click Stop.
- Confirm that the IP address of the connected server changes to that of an alternate server in the virtual disk status dialog.