Provisioning Server failover
By default, all Provisioning Servers within a site that can access a vDisk provide that vDisk to target devices. On shared storage, multiple Provisioning Servers access the same physical files, allowing a target device to establish a connection on an alternate Provisioning Server. This failover permits a connection to the active Provisioning Server is 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 vDisk provide that vDisk to target devices. For example, if a vDisk is replicated across three servers and one of the vDisks is updated, that vDisk 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 vDisks, the timestamps on each differ, resulting in vDisks that are no longer identical.
Provisioning Services does not support vDisk high availability on local storage in Private Image mode or that are currently in maintenance mode.
If load balancing is enabled and a server providing that vDisk fails, the load is automatically balanced between the target device and the remaining servers. If the load balancing option is not enabled, a single server is assigned, providing the vDisk to target devices. In such situations failover does not occur.
For information on automatically balancing the target device load between servers, refer to Managing Servers.
The Provisioning Server accessed by the target device does not necessarily become the one that accesses the vDisk on behalf of it. In addition, once connected, if one or more servers can access the vDisk 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 Provisioning Server.
- Right-click the connected Provisioning Server in the Console. Select Stream Services, then select Stop.
- Confirm that the IP address of the connected server changes to that of an alternate server in the vDisk status dialog.