Remote storage management mechanism and method

Abstract

The flow of work requests in a server driven process to process communication environment is described. Logical connections between processes and bus managers interfacing bus units to an I/O bus are assigned to connection groups for management by the bus managers. Each bus unit has its own connection groups for the logical connections. Bus unit resources are assigned to each connection group based on performance factors, and a series of bus unit messages are used to control the flow of work so that a group which has no more resources will not accept further work requests. The originator of the work requests will resequence rejected work requests and resend them when the connection group has freed up resources. A further mechanism is provided to facilitate work consistent with the server driven architecture when bus units do not have adequate DMA capabilities. Two ways of reversing control of transfer of work requests and data so that the server need not have master DMA capability are presented. Management of storage in a remote processor is used to transfer work and its associated data into storage accessible by a bus unit with slave DMA capability. The slave DMA bus unit then transfers the information into storage is manages. In another way of reversing the flow, a bus unit message is used to make the original server a requestor. The bus unit message contains information which varies the request sent by the requestor. In this manner, the server, which was the original requestor transfers information using its master DMA capability flow.