ovsdb-server

Section: Open vSwitch Manual (5)
Updated: DB Schema 1.1.0
Page Index

NAME

ovsdb-server - _Server database schema

Every ovsdb-server (version 2469 or later) always hosts an instance of this schema, which holds information on the status and configuration of the server itself46 This database is read-only46 This manpage describes the schema for this database46

TABLE SUMMARY

The following list summarizes the purpose of each of the tables in the _Server database. Each table is described in more detail on a later page.

Table: Purpose
Database: Databases46

Database TABLE

This table describes the databases hosted by the database server, with one row per database46 As its database configuration and status changes, the server automatically and immediately updates the table to match46

The OVSDB protocol specified in RFC 7047 does not provide a way for an OVSDB client to find out about some kinds of configuration changes, such as about databases added or removed while a client is connected to the server, or databases changing between read/write and read-only due to a transition between active and backup roles46 This table provides a solution: clients can monitor the table's contents to find out about important changes46

Traditionally, ovsdb-server disconnects all of its clients when a significant configuration change occurs, because this prompts a well-written client to reassess what is available from the server when it reconnects46 Because this table provides an alternative and more efficient way to find out about those changes, OVS 2469 also introduces the set_db_change_aware RPC, documented in ovsdb-server(7), to allow clients to suppress this disconnection behavior46

When a database is removed from the server, in addition to Database table updates, the server sends canceled messages, as described in RFC 7047 section 4461464, in reply to outstanding transactions for the removed database46 The server also cancels any outstanding monitoring initiated by monitor or monitor_cond requested on the removed database, sending the monitor_canceled RPC described in ovsdb-server(7)46 Only clients that disable disconnection with set_db_change_aware receive these messages46

Clients can use the _uuid column in this table as a generation number46 The server generates a fresh _uuid every time it adds a database, so that removing and then re-adding a database to the server causes its row _uuid to change46

Summary:

name: string
model: string, either clustered or standalone
schema: optional string
Clustered Databases:

connected
boolean

leader
boolean

cid
optional uuid

sid
optional uuid

index
optional integer

Details:

name: string: The database's name, as specified in its schema46
model: string, either clustered or standalone: The storage model: standalone for a standalone or active-backup database, clustered for a clustered database46
schema: optional string: The database schema, as a JSON string46 In the case of a clustered database, this is empty until it finishes joining its cluster46

Clustered Databases:

These columns are most interesting and in some cases only relevant for clustered databases, that is, those where the model column is clustered46

connected: boolean: True if the database is connected to its storage46 A standalone or active-backup database is always connected46 A clustered database is connected if the server is in contact with a majority of its cluster46 An unconnected database cannot be modified and its data might be unavailable or stale46
leader: boolean: True if the database is the leader in its cluster46 For a standalone or active-backup database, this is always true46
cid: optional uuid: The cluster ID for this database, which is the same for all of the servers that host this particular clustered database46 For a standalone or active-backup database, this is empty46
sid: optional uuid: The server ID for this database, different for each server that hosts a particular clustered database46 A server that hosts more than one clustered database will have a different sid in each one46 For a standalone or active-backup database, this is empty46
index: optional integer: For a clustered database, the index of the log entry currently exposed to clients46 For a given server, this increases monotonically46 When a client switches from one server to another in a cluster, it can ensure that it never sees an older snapshot of data by avoiding servers that have index less than the largest value they have already observed46
: For a standalone or active-backup database, this is empty46