Use these 2 TSM server options to prevent network bottleneck during backup schedules

In the Tivoli Storage Manager environment where many nodes try to initiate scheduled  operations simultaneously, you may need to manage scheduling throughput wisely in-order to make sure the TSM server does not get into network bottleneck. You can choose a different scheduling mode options for some schedules based upon the priority and available resources, and you can control how often client nodes contact the server to perform a scheduled operation.

Relation between SCHEDMODE and SERVERINITIATION parameters

Tivoli Storage Manager provides two scheduling modes - client-polling and server-prompted. The mode indicates how client nodes interact with the server for scheduling operations. With client-polling mode, client nodes poll the server for the next scheduled event. With server-prompted mode, the server contacts the nodes at the scheduled start time. 

By default, the server permits both scheduling modes. The default (ANY) allows nodes to specify either scheduling mode in their client options files. You can modify this scheduling mode.

Also Read: How to configure TSM Client Backup & Archive Schedules ?

If you modify the default server setting to permit only one scheduling mode, all client nodes must specify the same scheduling mode in their client options file. Clients that do not have a matching scheduling mode will not process the scheduled operations. The default mode for client nodes is client-polling. The scheduler must be started on the client node's machine before a schedule can run in either scheduling mode.

By default, clients contact the server (client-polling scheduling mode and SESSIONINITIATION=CLIENTORSERVER). If SESSIONINITIATION is set to the default CLIENTORSERVER value, you can use either client-polling or server-prompted scheduling modes. The client might start sessions with the server by communicating on the TCP/IP port that was defined with a server option. Server-prompted scheduling also can be used to prompt the client to connect to the server.

You can instead prevent clients from starting sessions, and allow only the server to start sessions with clients. To limit the start of backup-archive client sessions to the server only, do the following steps for each node

• Use the REGISTER NODE command or the UPDATE NODE command to change the value of the SESSIONINITIATION parameter to SERVERONLY, Specify the high-level address and low-level address options. These options must match what the client is using, otherwise the server will not know how to contact the client.

• Set the scheduling mode to server-prompted. All sessions must be started by server-prompted scheduling on the port that was defined for the client with the REGISTER NODE or the UPDATE NODE commands.

• Ensure that the scheduler on the client is started. You cannot use the client acceptor (dsmcad) to start the scheduler when SESSIONINITIATION is set to SERVERONLY.

If you modify the default so that the server permits only one scheduling mode for the server, all clients must specify the same scheduling mode in their client options file. Clients that do not have a matching scheduling mode do not process scheduled operations.

Also Read: How to configure TSM Server Administrative Schedules ?

To have clients poll the server for scheduled operations, run this command on TSM Server

set schedmodes polling

Ensure that client nodes specify the same mode in their client options files. 

To have the server prompt clients for scheduled operations, run this command on TSM Server

set schedmodes prompted

Ensure that client nodes specify the same mode in their client options files. 

To return to the default scheduling mode so that the server supports both client-polling and server-prompted scheduling modes, run this command on TSM Server

set schedmodes any

Client nodes can then specify either polling or prompted mode. Modifying the default scheduling mode on client nodes Users can set the scheduling mode on client nodes. They specify either the client-polling or the server-prompted scheduling mode on the command line or in the client user options file. (On UNIX and Linux systems, root users set the scheduling mode in the client system options file.