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 3.0.0              DB Schema 1.2.0                ovsdb-server(5)