The NUMBER OF CLUSTER NODES is clause and the NUMBER OF
    VAXCLUSTER NODES is clause have exactly the same effect. The
    option of using NUMBER OF CLUSTER NODES has been added to reflect
    the fact that Oracle Rdb can run on different hardware platforms (in
    addition to VAXclusters).

    Sets the upper limit on the maximum number of nodes in the
    cluster from which users can access the shared database. The
    default is 16 nodes. The range is 1 node to 96 nodes. The actual
    maximum limit is the current cluster limit.

    In some cases, after you have specified a particular number of
    users and nodes, doing a dump of the database root file will
    display a different number of nodes than the value you set. The
    following paragraphs explain why this occurs.

    The relationship between the number of users and the number of
    nodes supported on a database can be seen when you specify 2032
    users and 4 nodes in a SQL CREATE/ALTER DATABASE or RDO DEFINE
    /CHANGE DATABASE statement and then dump the database root file.
    The dump displays values of 2032 users and 41 nodes.

    To understand this relationship, Oracle Rdb uses a data structure
    called a TSN Block (TSNBLK). A TSN Block keeps track of
    transaction activity on a node and transaction information for
    each user on a particular node. Each TSN Block is owned by a
    particular node and can handle up to 50 users. For each group of
    50 users one TSNBLK is allocated per node to cover the maximum
    number of users and nodes the database is expected to support,
    which is determined as either one TSNBLK per node, or one TSNBLK
    per 50 users, whichever is larger. The maximum number of TSN
    blocks is equal to the value of the current maximum number of
    nodes that are supported for a database.

    For example, if the DBA specifies 2032 users and 4 nodes, this
    is calculated as 2032/50 for a total of 41 TSNBLKs and this
    equates to 41 nodes. The algorithm selects the maximum value
    of (number of nodes specified, number of nodes calculated). So in
    this example, 41 is the maximum calculated value (calculated 41 >
    specified 4).

    Had the DBA specified 2032 users and 50 nodes, 50 would be the
    maximum value for the number of nodes (specified 50 > calculated
    41) and 50 TSNBLKs would be allocated, one for each node.

    As another example, if the DBA specifies 50 users and 10 nodes,
    the maximum value is 10 nodes (specified 10 > calculated 1), so
    ten TSNBLKs would be allocated, one for each node.