1ovsdb-server(5) Open vSwitch Manual ovsdb-server(5)
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6 ovsdb-server - _Server database schema
7 Every ovsdb-server (version 2.9 or later) always hosts an instance of
9 this schema, which holds information on the status and configuration of
10 the server itself. This database is read-only. This manpage describes
11 the schema for this database.
12
14 The following list summarizes the purpose of each of the tables in the
15 _Server database. Each table is described in more detail on a later
16 page.
17 Table Purpose
19 Database Databases.
20
22 This table describes the databases hosted by the database server, with
23 one row per database. As its database configuration and status changes,
24 the server automatically and immediately updates the table to match.
25 The OVSDB protocol specified in RFC 7047 does not provide a way for an
27 OVSDB client to find out about some kinds of configuration changes,
28 such as about databases added or removed while a client is connected to
29 the server, or databases changing between read/write and read-only due
30 to a transition between active and backup roles. This table provides a
31 solution: clients can monitor the table’s contents to find out about
32 important changes.
33 Traditionally, ovsdb-server disconnects all of its clients when a sig‐
35 nificant configuration change occurs, because this prompts a well-writ‐
36 ten client to reassess what is available from the server when it recon‐
37 nects. Because this table provides an alternative and more efficient
38 way to find out about those changes, OVS 2.9 also introduces the
39 set_db_change_aware RPC, documented in ovsdb-server(7), to allow
40 clients to suppress this disconnection behavior.
41 When a database is removed from the server, in addition to Database ta‐
43 ble updates, the server sends canceled messages, as described in RFC
44 7047 section 4.1.4, in reply to outstanding transactions for the
45 removed database. The server also cancels any outstanding monitoring
46 initiated by monitor or monitor_cond requested on the removed database,
47 sending the monitor_canceled RPC described in ovsdb-server(7). Only
48 clients that disable disconnection with set_db_change_aware receive
49 these messages.
50 Clients can use the _uuid column in this table as a generation number.
52 The server generates a fresh _uuid every time it adds a database, so
53 that removing and then re-adding a database to the server causes its
54 row _uuid to change.
55 Summary:
57 name string
58 model string, either clustered or standalone
59 schema optional string
60 Clustered Databases:
61 connected boolean
62 leader boolean
63 cid optional uuid
64 sid optional uuid
65 index optional integer
66 Details:
68 name: string
69 The database’s name, as specified in its schema.
70 model: string, either clustered or standalone
72 The storage model: standalone for a standalone or active-backup
73 database, clustered for a clustered database.
74 schema: optional string
76 The database schema, as a JSON string. In the case of a clus‐
77 tered database, this is empty until it finishes joining its
78 cluster.
79 Clustered Databases:
81 These columns are most interesting and in some cases only relevant for
83 clustered databases, that is, those where the model column is clus‐
84 tered.
85 connected: boolean
87 True if the database is connected to its storage. A standalone
88 or active-backup database is always connected. A clustered data‐
89 base is connected if the server is in contact with a majority of
90 its cluster. An unconnected database cannot be modified and its
91 data might be unavailable or stale.
92 leader: boolean
94 True if the database is the leader in its cluster. For a stand‐
95 alone or active-backup database, this is always true.
96 cid: optional uuid
98 The cluster ID for this database, which is the same for all of
99 the servers that host this particular clustered database. For a
100 standalone or active-backup database, this is empty.
101 sid: optional uuid
103 The server ID for this database, different for each server that
104 hosts a particular clustered database. A server that hosts more
105 than one clustered database will have a different sid in each
106 one. For a standalone or active-backup database, this is empty.
107 index: optional integer
109 For a clustered database, the index of the log entry currently
110 exposed to clients. For a given server, this increases monotoni‐
111 cally. When a client switches from one server to another in a
112 cluster, it can ensure that it never sees an older snapshot of
113 data by avoiding servers that have index less than the largest
114 value they have already observed.
115 For a standalone or active-backup database, this is empty.
117Open vSwitch 2.10.1 DB Schema 1.1.0 ovsdb-server(5)