Echelon OpenLNS Commissioning Tool - Manual (Page 250)

234 Maintaining Networks
25. Compare the recovered OpenLNS network database to your expected results. Because network
recovery occurs while OpenLNS CT is OffNet, required changes to device configuration
properties are stored in the OpenLNS network database instead of being propagated to the
network. Once you have checked the recovered OpenLNS network database and validated your
OpenLNS CT network design, change the management mode to OnNet. To do this, click
Add-ins, click LonWorks Network, click Network Properties, click the Network Interface tab,
and under Management Mode, select OnNet. If changes to device configurations are required,
OpenLNS CT will prompt you to resynchronize the network with the OpenLNS network database
(recommission devices).
Network Recovery vs. Database Backup
Even though you can use network recovery to rebuild an entire network database, you should not use
recovery as a replacement for backing up your OpenLNS CT network design. A backup is faster, more
accurate, and more reliable than using network recovery. You should therefore regularly backup your
OpenLNS CT network design as the primary means of protecting against drawing and database loss. If
your application warrants greater protection, you can use a redundant array of independent disks
(RAID) for the OpenLNS Server. For maximum performance and reliability, use a RAID 5 disk array.
Some of the advantages of regularly performing database backups over using network recovery are as
follows:
• Speed. Creating and restoring an OpenLNS CT backup file is much faster than recovering a
network. To recover the network, the OpenLNS Server must scan the network to discover all the
devices, upload a small portion of the overall network configuration stored in each device, and
then create a drawing and network database based on the data collected from the physical devices.
This data collection and reconstruction process generally grows with the complexity of the
network (the more devices, network variables, channels, and connections in a network, the more
complex the network is considered to be).
• Accuracy. Recovery only recovers attributes and properties stored in the devices themselves;
information that is not stored in devices, such as device names and the specified hubs and targets
in connections, may not be recovered.
Recovery may fail to create an exact duplicate of the original database. Specifically, if you
compare a recovered database to the original database, there will be differences because there are
many objects, properties, and attributes that cannot be identified uniquely and unambiguously.
For example, the handles assigned to devices, routers, and so on will probably differ, and
connection hubs and targets may change.
Recovery may also be incomplete if the network itself is inconsistent. A network may become
inconsistent if, for example, some of the devices have failed or are powered off, or if the network
tool failed while updating the configuration of a series of devices. In such a case, some devices
would contain new configuration data while others would have the old data. When recovering this
network, OpenLNS CT will not be able to distinguish the new configuration data from the old.
• Reliability. Although recovery is designed to be as reliable as possible, the successful recovery of
a given network depends on that network being fully functional, properly configured, and not
saturated by regular network traffic. Additionally, authentication can prevent parts of a network
from being recovered.
In the event you cannot restore a network from a database backup or your OpenLNS database and
OpenLNS CT drawing files are lost, you can use recovery. However, the following inconsistencies
may result in changes to network variable and address table entry configurations:
• If a bound source network variable does not have any associated source or target, it is marked as
unbound and removed from the associated connection.
• If a bound dedicated message tag does not have any targets, its address table entry is marked as
empty and removed from the associated connection.