Echelon LNS - Manual (Page 272)

LNS Programmer's Guide 258
a function of the number of devices, network variables, channels, and
connections.
• Network recovery only recovers attributes and properties stored in the
devices on the network. LNS-specific information such as subsystem
names and device names is not recovered. In addition, the recovery
process will not create an exact duplicate of the original database. If you
compare a recovered database to the original database, there will be
differences, as there are many objects, properties and attributes that
cannot be identified uniquely and unambiguously by the recovery process.
For example, the handles assigned to devices and routers might differ,
and connection hubs and targets may differ if you were to compare the
original database with the recovered database. A network recovery may
also be incomplete if the network itself is inconsistent. A network could
become inconsistent if the network tool failed while updating the
configuration of a series of devices. In this case, some devices would
contain "new" information while other devices contain "old" information.
When recovering this network, there is no way for the LNS Object Server
to determine which information is out-of-date.
For more information on inconsistencies that may exist between the
original database and the database created by the network recovery
process, see the next section, Network Recovery Inconsistencies.
• Network recovery cannot recover network variables, monitor sets or
monitor points defined on a Network Service Device, or any connections
involving a Network Service Device.
• Restoring a network database from a backup is more reliable. Successful
recovery of a database from a given network relies on that network being
properly configured, and not saturated with regular network traffic when
the recovery is performed. Additionally, authentication can prevent parts
of a network from being recovered.
Network Recovery Inconsistencies
It is possible that some network inconsistencies will be created while recovering a
network database. Before performing a network recovery, you should review the
following list of inconsistencies and limitations of network recovery:
• Recovery of networks with unsupported configurations is not possible.
Examples of unsupported network configurations include networks with
multiple authentication keys, or networks with multiple domains.
• If a bound network variable has no associated source or target, it is
marked as unbound. No address is associated with this network variable.
This could occur if only one of two devices that take part in a connection
is recovered successfully.
• If a bound declared message tag has no targets, its address table entry is
marked as empty.
• Any address table entries that are not associated with a network variable
or message tag (source or target) are marked as empty. A lost source or a
lost target may create this situation. Group use counts are updated as
necessary, and group IDs are freed as necessary.