ovsdb-server(5) Open vSwitch Manual ovsdb-server(5)
NAME
ovsdb-server - _Server database schema
Every ovsdb-server (version 2.9 or later) always hosts an instance of
this schema, which holds information on the status and configuration of
the server itself. This database is read-only. This manpage describes
the schema for this database.
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 Databases.
Database TABLE
This table describes the databases hosted by the database server, with
one row per database. As its database configuration and status changes,
the server automatically and immediately updates the table to match.
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 roles. This table provides a
solution: clients can monitor the table’s contents to find out about
important changes.
Traditionally, ovsdb-server disconnects all of its clients when a sig‐
nificant configuration change occurs, because this prompts a well-writ‐
ten client to reassess what is available from the server when it recon‐
nects. Because this table provides an alternative and more efficient
way to find out about those changes, OVS 2.9 also introduces the
set_db_change_aware RPC, documented in ovsdb-server(7), to allow
clients to suppress this disconnection behavior.
When a database is removed from the server, in addition to Database ta‐
ble updates, the server sends canceled messages, as described in RFC
7047 section 4.1.4, in reply to outstanding transactions for the re‐
moved database. The server also cancels any outstanding monitoring ini‐
tiated by monitor or monitor_cond requested on the removed database,
sending the monitor_canceled RPC described in ovsdb-server(7). Only
clients that disable disconnection with set_db_change_aware receive
these messages.
Clients can use the _uuid column in this table as a generation number.
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 change.
Summary:
name string
model string, one of clustered, relay, or
standalone
schema optional string
connected boolean
Clustered Databases:
leader boolean
cid optional uuid
sid optional uuid
index optional integer
Details:
name: string
The database’s name, as specified in its schema.
model: string, one of clustered, relay, or standalone
The storage model: standalone for a standalone or active-backup
database, clustered for a clustered database, relay for a relay
database.
schema: optional string
The database schema, as a JSON string. In the case of a clus‐
tered database, this is empty until it finishes joining its
cluster. In the case of a relay database, this is empty until it
connects to the relay source.
connected: boolean
True if the database is connected to its storage. A standalone
database is always connected. A clustered database is connected
if the server is in contact with a majority of its cluster. A
relay database is connected if the server is in contact with the
relay source, i.e. is connected to the server it syncs from. An
unconnected database cannot be modified and its data might be
unavailable or stale.
Clustered Databases:
These columns are most interesting and in some cases only relevant for
clustered databases, that is, those where the model column is clus‐
tered.
leader: boolean
True if the database is the leader in its cluster. For a stand‐
alone or active-backup database, this is always true. For a re‐
lay database, this is always false.
cid: optional uuid
The cluster ID for this database, which is the same for all of
the servers that host this particular clustered database. For a
standalone, active-backup or relay database, this is empty.
sid: optional uuid
The server ID for this database, different for each server that
hosts a particular clustered database. A server that hosts more
than one clustered database will have a different sid in each
one. For a standalone, active-backup or relay database, this is
empty.
index: optional integer
For a clustered database, the index of the log entry currently
exposed to clients. For a given server, this increases monotoni‐
cally. 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 observed.
For a standalone, active-backup or relay database, this is
empty.
Open vSwitch 3.3.1 DB Schema 1.2.0 ovsdb-server(5)