Product Documentation

Provisioning Server failover

Feb 24, 2016
By default, all Provisioning Servers within a site that can access a vDisk can provide that vDisk to target devices. Multiple Provisioning Servers can access the same physical files located on shared storage, which allows a target device to establish a connection on an alternate Provisioning Server if the connection to the active Provisioning Server is interrupted for any reason. A target device does not experience any disruption in service or loss of data when failover occurs.
Note: For implementations that use vDisk replication, if a server failover occurs, only those servers with access to an identical replicated vDisk can provide that vDisk to target devices. For example; if vDisk is replicated across three servers hard drives and then one of the vDisks is updated, that vDisk is no longer identical and will not be considered if a server failover occurs. Even if the same exact update is made to two of the vDisks, the timestamps on each will differ, therefore the vDisks are no longer identical.
Note: Provisioning Services does not support the high availability of vDisks on local storage that are in Private Image mode or that are currently in maintenance (read/write enabled).
If load balancing is enabled for the vDisk and a server providing that vDisk should fail, Provisioning Services automatically balances the target device load between the remaining servers. If the load balancing option is not enabled, a single server is assigned to provide the vDisk to target devices, therefore failover will not occur.
Note: For information on configuring Provisioning Services to automatically balance the target device load between servers, refer to Balancing the Target Device Load on Provisioning Servers.

Highly Available Implementation

The Provisioning Server that a target device accesses to login does not necessarily become the Provisioning Server that accesses the vDisk on behalf of the target device. In addition, once connected, if one or more Provisioning Servers can access the vDisk for this target device, the server that is least busy is selected.

To purposely force all target devices to connect to a different Provisioning Server, while avoiding having targets timeout and attempt to reconnect to the current server, stop the Stream Service on that server. Upon shutdown, the Stream Service will notify each target device to re-login to another server.

Testing Target Device Failover

To ensure that devices can failover successfully, complete the following:

  1. Double-click the vDisk status icon on the target device and then note the IP address of the connected Provisioning Server.
  2. Right-click the connected Provisioning Server in the Console. Select Stream Services, then select Stop.
  3. Confirm that the IP address of the connected Provisioning Server changes to that of an alternate Provisioning Server in the vDisk status dialog on the target device.