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
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.
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
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
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:
- Double-click the vDisk status icon on the target device and then 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 Provisioning Server changes to that of an alternate Provisioning Server in the vDisk status dialog on the target device.