BMC AMI Storage IAM Overview
The IAM product is different from many other VSAM performance enhancement products. Rather than trying to tweak VSAM to work faster, the IAM approach starts by using a different underlying file structure and data organization. This innovation, coupled with performance-oriented algorithms and coding techniques, results in significant proven performance benefits.
The IAM product is being used to achieve the following benefits:
- Reduction of computing costs
- Reduction of CPU time
- Reduction of EXCPs
- Reduction of DASD space utilization
- Reduce nightly batch processing window
- Delay processor and DASD upgrades
The IAM product is available as a base product that supports KSDS, ESDS, and RRDS type of files. It provides support for Alternate Indexes (AIX) as well. The IAM/PLEX feature provides Sysplex record level sharing support. A free trial version of IAM is available for users to evaluate the IAM product. If requested, it will also include the IAM/PLEX optional feature.
BMC AMI Storage IAM is a high-performance indexed access method for z/OS that offers numerous advantages over the IBM provided VSAM access method. IAM files exist on DASD in a different file structure than VSAM data sets, with IAM providing a VSAM compatible API (Application Programming Interface) for KSDS, RRDS, and ESDS file types. IAM/AIX provides support for alternate indexes. Existing as non-VSAM data sets provides IAM with capabilities to eliminate the 4.3 GB file size restriction in VSAM for files that are not DFSMS Extended Format with Extended Addressability, and to choose a block size that will optimize space utilization on each of the different type of DASD devices and architectures available. Along with IAM's unique file structure, described in a subsequent section and IAM's Data Compression feature, user data stored in an IAM file typically requires substantially less DASD space than when stored in a VSAM cluster.
The basic principle of IAM is to intelligently utilize virtual storage to reduce the need to perform physical I/O to look up and retrieve data. This is accomplished by using the sophisticated IAM Real-Time Tuning concept to manage buffers, and by keeping the index for files in virtual storage while they are being processed. IAM requires a minimum one I/O to retrieve any explicitly identified record within the data set. All the index I/O and index buffers used by VSAM are eliminated.
This section provides more information about the following topics: