Load Factors For Sync Nodes in a Multi-Node Riva Deployment

  • Updated

In a multi-node deployment of Riva, it is possible to determine a load factor for each sync node. A node's load factor represents which fraction of users is going to be assigned to that sync node.

Changing the load factors does not change the assignment of existing users to the nodes. It affects only the assignment of new users. As sync users are added to the system, the number of users per node gradually ramps up to values that are consistent with the new load factors.

 

Notes:

  • By default, a new sync node is assigned a load factor of zero.
  • Only whole numbers are used to express the load factors. See the example.
     

Example:

  • Three sync nodes are configured to sync one-third of each of the users. The load factors are expressed as 1,1,1. They could also be expressed as 33,33,33 or 200,200,200. Any whole number used three times in a row represents one-third of the users for every node.
  • Three hundred users are assigned to the nodes. The nodes now have this many users: 100, 100, and 100.
  • The load factors are changed to 1,2,1, which represents 25% of users for the first node, 50% for the second, and 25% for the third.
  • 100 users are added. The nodes now have respectively 100, 200, and 100 users, which is consistent with the configured load factors.
  • If instead of 100 users, only 72 users are added, the nodes have respectively 100, 172, and 100 users. Because existing users are not reassigned from one node to another, the ratios are not yet 1,2,1, but the system is ramping up towards those ratios. When 28 more users are added (100-72=28), then the number of users per node should match the load factors.
     

Minute variations may occur. For example, if a user was once assigned to a node, then temporarily disappears, and then reappears, it is re-assigned to the same node that it had been originally assigned to, even if the resulting number of users per node does not match the load factors exactly. (The return of a user to its original node is referred to as sticky behaviour. For more information, see Global Sync Configuration.)

To assign the load factors to a group of nodes:

  1. Start the Riva Manager application. On the menu bar, select Tools, and then choose Configure Remote Management.

  2. In the left pane, under Clients, select Global Sync Configuration.

  3. In the right pane, under Global Identification, select the Use load factors check box.

    Note: This is possible only if the Mode is set to Provider.

  4. In the Load factors field, enter the whole numbers followed by commas, except that nothing follows the last whole number.

    Examples in a 3-node setup:

    • To assign one-half of the new users to each of the two nodes and zero new users to the third node, any of the following strings works: 1,1,0, 50,50,0, or 200,200,0. Any pair of identical whole numbers followed by zero represents the fractions 50%, 50%, and 0%.
    • To assign one-third of the new users to every node.
       
  5. Select Save.

    From now on, the Global Sync Configuration (GSC) service refers to the load factors when assigning new users to the sync nodes.

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