Modified Indirect Data Address Words (MIDAWs) are a channel

Channel I/O

In computer science, channel I/O is a generic term that refers to a high-performance input/output architecture that is implemented in various forms on a number of computer architectures, especially on mainframe computers...

 programming capability of the IBM System z9

System z9

IBM System z9 is a line of IBM mainframe. It was announced on July 25, 2005 and the first models were available on September 16, 2005. The System z9 also marks the end of the previously used eServer zSeries naming convention, and it is the last z/Architecture 1 machine.- Background :System z9 is a...

 processor. The MIDAW facility is an extension to the pre-existing Indirect Data Address Word (IDAW) channel programming capability, providing support for more efficient FICON

FICON

FICON is the IBM proprietary name for the ANSI FC-SB-3 Single-Byte Command Code Sets-3 Mapping Protocol for Fibre Channel protocol. It is a FC layer 4 protocol used to map both IBM’s antecedent channel-to-control-unit cabling infrastructure and protocol onto standard FC services and infrastructure...

 channel programs.

MIDAWs allow ECKD channel programs to read and write to many storage locations using one channel command, which means fewer signals up and down the channel are required to transfer the same amount of data. This reduction is particularly noticeable for Extended Format data sets

Data set (IBM mainframe)

data set , dataset , is a computer file having a record organization. The term pertains to the IBM mainframe operating system line, starting with OS/360, and is still used by its successors, including the current z/OS. Those systems historically preferred this term over a file...

, accessed through Media Manager. Examples include Extended Format Sequential data sets, Extended Format VSAM data sets and certain types of DB2

IBM DB2

The IBM DB2 Enterprise Server Edition is a relational model database server developed by IBM. It primarily runs on Unix , Linux, IBM i , z/OS and Windows servers. DB2 also powers the different IBM InfoSphere Warehouse editions...

 tablespaces. While each of these data set organizations have alternatives, each has a distinct set of advantages, whether in the area of performance, space saving (through hardware-assisted data compression

Data compression

In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....

), or scalability (by allowing an individual data set to exceed 4 GiB).