Cisco N5010P-N2K-BE, Software Configuration Manual

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Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
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Chapter 21 Using Cisco Fabric Services
CFS Support for Applications
CFS Merge Support
CFS Merge is supported for CFS distribution over Fibre Channel.
An application keeps the configuration synchronized in a SAN fabric through CFS. Two such fabrics
might merge as a result of an ISL coming up between them. These two fabrics could have two different
sets of configuration information that need to be reconciled in the event of a merge. CFS provides
notification each time an application peer comes online. If a fabric with M application peers merges with
another fabric with N application peers, and if an application triggers a merge action on every
notification, a link-up event results in M*N merges in the fabric.
CFS supports a protocol that reduces the number of merges required to one by handling the complexity
of the merge at the CFS layer. This protocol runs per application per scope. The protocol involves
selecting one switch in a fabric as the merge manager for that fabric. The other switches do not have a
role in the merge process.
During a merge, the merge manager in the two fabrics exchange their configuration databases with each
other. The application on one of them merges the information, decides if the merge is successful, and
informs all switches in the combined fabric of the status of the merge.
In case of a successful merge, the merged database is distributed to all switches in the combined fabric
and the entire new fabric remains in a consistent state. You can recover from a merge failure by starting
a distribution from any of the switches in the new fabric. This distribution restores all peers in the fabric
to the same configuration database.
CFS Support for Applications
The following topics describe the CFS capabilities that support applications:
•
CFS Application Requirements, page 21-6
• Enabling CFS for an Application, page 21-7
•
Locking the Network, page 21-8
• Committing Changes, page 21-8
•
Discarding Changes, page 21-9
• Saving the Configuration, page 21-9
•
Clearing a Locked Session, page 21-9
CFS Application Requirements
All switches in the network must be CFS capable. Switches that are not CFS capable do not receive
distributions and result in part of the network not receiving the intended distribution.
CFS has the following requirements:
• Implicit CFS usage—The first time you issue a CFS task for a CFS-enabled application, the
configuration modification process begins and the application locks the network.
•
Pending database—The pending database is a temporary buffer to hold uncommitted information.
The uncommitted changes are not applied immediately to ensure that the database is synchronized
with the database in the other switches in the network. When you commit the changes, the pending
database overwrites the configuration database (also known as the active database or the effective
database).