Reduces network traffic by directing the data over SAN, rather than
the LAN.
Enables optimal utilization of resources by enabling load-balancing
between several MediaAgents and available resources.
Using Dynamic Drive Sharing (DDS), all the libraries and drives available
in the SAN can be shared by the MediaAgents that have access to the SAN.
The following illustration represents a library shared via SAN with dynamic
drive sharing (DDS). Three MediaAgents share a tape library with four drives.
Note that any of these MediaAgents can also be attached to additional
libraries. Also the library can have additional drives which can be configured
for other MediaAgents. In addition, you can also configure one or more MediaAgents
as failover candidates to ensure that all the jobs using the library are
performed without interruption in the event of a failure in any one MediaAgent.
In the above illustration:
All the MediaAgents share the same four drives, using Dynamic Drive Sharing.
Each MediaAgent has a drive pool which is grouped under one master drive
pool for the library.
The media changer can be controlled by some or all MediaAgents if they are
configured as failover library controller candidates.
Within the software, the SAN environment also provides the facility to configure
multiple controllers across MediaAgents that access a library. See
Library Controllers, for more information.
WARNING
Stop and disable Removable Storage
Management (RSM) service on all Windows 2000 on a SAN, which can detect
the shared tape/optical drives that are configured. These include other
MediaAgents and even other machines which do not have any components
installed. This is a very stringent requirement as data corruption occurs
if both RSM and MediaAgent running on any machine in the SAN access
the same drive at the same time.
We strongly recommend that in a SAN based environment, hardware zoning
of tape drives be implemented so that only the designated MediaAgents
can detect and control the devices. This will minimize unnecessary monitoring
and access to the devices from non-designated machines.
When multiple MediaAgents share the libraries and drives in the SAN environment,
the DDS configuration process can be automated. This can done by first configuring
the library in any one of the MediaAgents that share the library. Subsequently,
the DDS setup is automatically established in all the other MediaAgents, without
any user-interaction.
You can also manually configure the library with a DDS configuration for each
of the MediaAgents sharing the library. This method of configuration, allows you
to customize the configuration of library controllers on all or specific MediaAgents.
The option
to automatically create/configure DDS DrivePools is not available for NAS-attached libraries; Dynamic Drive Sharing must be
configured manually. For instructions on how to configure DDS for
NAS-attached libraries, see
Configure NAS-attached Libraries Shared Across a SAN .
This feature provides the facility to configure a device with DDS using different
HBAs on the same MediaAgent.
Once enabled, a MediaAgent with multiple HBA zoned to see the same drive(s) will
have multiple devices (one for each HBA)appearing in the Library and Drive Configuration
window. If the Auto create DDS Drive Pool option in Library Properties
is enabled and if the drive(s) on any MediaAgent (local or remote) are configured,
then when the MediaAgent Service are re-started, the system will automatically add
one drive pool for each instance of the drive(s) as seen by the HBAs on that MediaAgent.
This feature is not supported for NAS-attached libraries.
Right -click the library for which you wish to create the DDS and then
click Properties.
Enable the Auto Configure Failover Library Controllers option.
Stop and restart the MediaAgent services on the MediaAgent computer.
WARNING
If you have more than one HBA,
and you do not wish to configure the library in a DDS setup as described
above, you will see more than on library when you detect the device
in the Library and Drive Configuration window.
You must configure only one of those detected libraries. Configuring
all the libraries may cause undesirable results, resulting in data loss.
To ensure that all library related jobs are performed without interruption in
the event of a failure in the MediaAgent controlling the media changer, the software
provides the facility to configure the active library controller and failover library
controller candidates in the MediaAgents that share a library in the SAN environment.
This feature provides the following benefits:
Automatic switching of the active library controller to the next available
failover library controller candidate, in the event of a failure or non availability
of the MediaAgent controlling the active library controller.
Facility to manually switch an active library controller to the next available
failover library controller candidate, if the machine hosting the active library
controller has a problem or for the purpose of balancing the workload. Failover
library controller setup can be configured on MediaAgents that access a library
in the SAN environment.
The MediaAgent automatically switches an active library controller to the next
available failover library controller candidate when the following events occur:
The machine hosting the active library controller is powered off or not
accessible due to a network failure.
Services in the machine hosting the active library controller is not started
or running.
The MediaAgent associated with the active library controller is marked offline
from the CommCell Console.
