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 re‐
45 moved database. The server also cancels any outstanding monitoring ini‐
46 tiated 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, one of clustered, relay, or
59 standalone
60 schema optional string
61 connected boolean
62 Clustered Databases:
63 leader boolean
64 cid optional uuid
65 sid optional uuid
66 index optional integer
67 Details:
69 name: string
70 The database’s name, as specified in its schema.
71 model: string, one of clustered, relay, or standalone
73 The storage model: standalone for a standalone or active-backup
74 database, clustered for a clustered database, relay for a relay
75 database.
76 schema: optional string
78 The database schema, as a JSON string. In the case of a clus‐
79 tered database, this is empty until it finishes joining its
80 cluster. In the case of a relay database, this is empty until it
81 connects to the relay source.
82 connected: boolean
84 True if the database is connected to its storage. A standalone
85 database is always connected. A clustered database is connected
86 if the server is in contact with a majority of its cluster. A
87 relay database is connected if the server is in contact with the
88 relay source, i.e. is connected to the server it syncs from. An
89 unconnected database cannot be modified and its data might be
90 unavailable or stale.
91 Clustered Databases:
93 These columns are most interesting and in some cases only relevant for
95 clustered databases, that is, those where the model column is clus‐
96 tered.
97 leader: boolean
99 True if the database is the leader in its cluster. For a stand‐
100 alone or active-backup database, this is always true. For a re‐
101 lay database, this is always false.
102 cid: optional uuid
104 The cluster ID for this database, which is the same for all of
105 the servers that host this particular clustered database. For a
106 standalone, active-backup or relay database, this is empty.
107 sid: optional uuid
109 The server ID for this database, different for each server that
110 hosts a particular clustered database. A server that hosts more
111 than one clustered database will have a different sid in each
112 one. For a standalone, active-backup or relay database, this is
113 empty.
114 index: optional integer
116 For a clustered database, the index of the log entry currently
117 exposed to clients. For a given server, this increases monotoni‐
118 cally. When a client switches from one server to another in a
119 cluster, it can ensure that it never sees an older snapshot of
120 data by avoiding servers that have index less than the largest
121 value they have already observed.
122 For a standalone, active-backup or relay database, this is
124 empty.
125Open vSwitch 2.17.0 DB Schema 1.2.0 ovsdb-server(5)