Types of hosts used in a common dump queue
The master scheduler (MS) is the DFSMShsm host that manages all of the dump requests in the CDQ. All dump requests are sent to it, and it assigns work to all of the other hosts in the group that are eligible to process requests from the CDQ. Each group needs a master scheduler to manage CDQ processing for the group; otherwise, dump requests are processed locally.
The other principal types of DFSMShsm hosts are the submitting host and the processing host.
- Submitting host
- Host that receives requests from commands and, using XCF messaging, sends it to the master scheduler host. Performs command complete processing and posts the user that the command has completed.
- Master scheduler (MS)
- Accepts requests from submitting host members and locally submitted requests and maintains them as a single common queue of all requests for the CDQ function. The master scheduler can be the submitting host – in this case the command is not sent.
- Assigns or distributes the requests among the available tasks across all of the eligible hosts (processing hosts) connected to the CDQ while balancing the requests among all the hosts.
- Manages "work completed" messages received from a processing host to support functions like stacking.
- Sends "command complete" messages back to the submitting host.
- Processing host
- Receives assigned work requests from the master scheduler and places them on its local queue for processing.
- Sends "work complete" messages back to the master scheduler with specific protocols to support functions like stacking.
- The processing host could be the submitting host and/or the master scheduler host.
Figure 1 shows a CDQ group where:
- HSM1 is the submitting and processing host
- HSM2 is the master scheduler and processing host. It receives all requests, managing them on a single queue, and distributes the requests among the eligible hosts connected to the common queue, through XCF messaging.
- HSM3 is a processing host.
Figure 1. CDQ Host Types