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5686-081 IBM VSE/VSAM for VM Version 6 Release 1

IBM EMEA Sales Manual
Revised:  August 02, 2005.

Table of contents  Document options 
TOC Link Abstract TOC Link Technical Description
TOC Link Product Positioning TOC Link Planning Information
TOC Link Highlights TOC Link Security, Auditability, and Control
TOC Link Description  
 
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Abstract

(No Longer Available as of September 30, 2005)

(Program Services Discontinued as of February 28, 2007)

VSE/VSAM* for VM now supports hardware-assisted data compression. This capability helps to improve system performance and reduce your total costs of computing.

Hardware-Assisted Data Compression

This new version of VSE/VSAM for VM now supports data compression for VSAM datasets. You can easily select which datasets to store and hold in memory as compressed datasets and which datasets should remain expanded. VSE/VSAM also supports software data compression (if you do not have the hardware-assist feature on your processor). Data compression helps to reduce your computing costs by:

  • Using significantly less disk space
  • Reducing channel traffic

Additionally, VSE/VSAM for VM improves your system performance by exploiting the hardware data compression feature (when available). Hardware data compression significantly reduces the processor time required to perform data compression.

Compatibility with your Existing Applications

No changes are required to your application program to realize the benefits of data compression and improved exploitation of 31-bit addressing. However, you must specify which files are to be compressed by VSAM.
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Product Positioning

VSE/VSAM, originally the access method for the VSE operating system, is widely accepted by VM customers and is a prerequisite for several VM products. VSE/VSAM is designed to operate with direct access devices and to support both direct and sequential processing.

VSE/VSAM for VM Version 6 Release 1 is extracted from VSE/ESA Central Functions Version 6 Release 1, which is a base program of VSE/ESA Version 2 Release 1.

Therefore, a customer who has licensed VSE Central Functions Version 6 can get VSE/VSAM for VM Version 6 without charge for the same machine.
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Highlights

  • Supports data compression for VSAM datasets

  • Improves system performance through hardware data compression

  • Reduces the processor time required to perform data compression

  • Requires no changes to application programs

  • Provides additional CMS virtual storage constraint relief below the 16 MB line

  • Supports RAMAC Array Family

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Description

Data Compression for VSAM datasets

VSE/VSAM for VM Version 6 Release 1 supports data compression for VSAM datasets. You can easily select which datasets to store and hold in memory as compressed datasets, and which datasets should remain expanded. VSAM will exploit the S/390 hardware-assisted compression feature, if available on the processor; otherwise, data compression is provided by software algorithms. Data compression provides the following benefits:

  • Requires significantly less disk space.
  • Reduces channel traffic.
  • Stores more data records within a 4-GB file.

Most application programs can use data compression. No changes are required to realize the benefits of data compression and inmproved exploitation of 31-bit addressing. You only need to specify which files are to be compressed.

Further 31-bit Exploitation

The exploitation of 31-bit addressing, which was introduced with VSE/VSAM Version 2 Release 2, is continued and provides additional CMS virtual storage constraint relief below the 16 MB line. The following VSAM control blocks are moved above the 16 MB line:

  • Place Holder (PLH)

  • Buffer Control Block (BCB)

  • Buffer Subpool Header (BSPH)

  • Buffer Header (BHD)

Device support

IBM RAMAC Array Family

The IBM RAMAC Array Family consists of high-performance RAID-5 (redundant array of independent disks - level five) fault tolerant disk arrays. Earlier levels of VSE/VSAM for VM support both the RAMAC Array DASD, model 9391, and the RAMAC Array Subsystem, model 9394. VSE/VSAM for VM Version 6 Release 1 provides performance enhancements for the RAMAC Array DASD, model 9391. IBM VSE/VSAM for VM Version 6 Release 1 also supports the newest members of the RAMAC Array Family.
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Technical Description
TOC Link Operating Environment TOC Link Hardware Requirements TOC Link Software Requirements


Operating Environment

See Hardware and Software Requirements.

Hardware Requirements

IBM VSE/VSAM for VM Version 6 Release 1 supports all IBM processors currently supported by IBM VM/ESA Version 2 Release 1, especially in its subcomponents CMSDOS or GCS, respectively. A list of devices supported by IBM VSE/VSAM for VM Version 6 Release 1 can be found in the "VSE/VSAM User's Guide and Application Programming" (SC33-6632).

The information on which processors and devices are supported in VM can be found in the General Information Manual and other publications of the specific VM release.

Software Requirements

IBM VSE/VSAM for VM Version 6 Release 1 runs with IBM VM/ESA Version 2 Release 1 or later.

Overview of VSAM Releases supported on VM Releases:

+-----------------+--------+--------+--------+
|                 |VSE/VSAM|VSE/VSAM|VSE/VSAM|
|                 |  V2R1  |  V2R2  |  V6R1  |
|                 | Support| Support| Support|
|  VM Release     |        |        |        |
+-----------------+--------+--------+--------+
|  VM/ESA Rel 1.5 |   Yes  | No (*) |   No   |
|  (370 Feature)  |        |        |        |
+-----------------+--------+--------+--------+
|  VM/ESA Rel 1.1 |   Yes  | No (*) |   No   |
+-----------------+--------+--------+--------+
|  VM/ESA Rel 2.0 |   Yes  | No (*) |   No   |
+-----------------+--------+--------+--------+
|  VM/ESA Rel 2.1 |   Yes  |   Yes  |   No   |
+-----------------+--------+--------+--------+
|  VM/ESA Rel 2.2 |   No   |   Yes  |   No   |
+-----------------+--------+--------+--------+
|  VM/ESA V2 Rel 1|   No   |   Yes  |  Yes   |
+-----------------+--------+-----------------+
| NOTE (*):  When VSE/VSAM V2.2 or V6.1 or   |
| VSE/ESA is licensed, VSE/VSAM V2.1 can be  |
| ordered without charge.                    |
+--------------------------------------------+
 

Compatibility

IBM VSE/VSAM for VM Version 6 Release 1 is compatible with IBM VSE/VSAM Version 2. Files, programs, and jobs that were created under IBM VSE/VSAM Version 2 can be used without changes.

To activate data compression, only a minor modification to AMSERV command streams is required.

Limitations

Data Compression

Programs that are not properly coded and programs that use Control Interval Mode (MACRF=CNV) cannot exploit VSAM /lsr compression.

4-GB Limit

Although the limitation that a VSAM data set cannot hold more than 4 GB (4,294,967,296 bytes) is still in effect, more data can effectively be stored using data compression.

Performance Considerations

IBM VSE/VSAM for VM Version 6 Release 1 performance and capacity have been enhanced in the support of S/390 Hardware assisted data compression.

Hardware data compression, supported by VSE/VSAM will allow data compression at considerably lower additional CPU-time cost than equivalent software compression. DASD requirements for compressed VSAM data sets will be reduced. The same applies to the physical DASD I/Os, depending on the individual customer environment.

Virtual Storage Constraint Relief (VSCR)

The exploitation of 31-bit addressing, which was introduced with IBM VSE/VSAM Version 2 Release 2, is continued and provides additional VSCR below the 16 MB line:

  • VSAM access control blocks are moved above the 16 MB line (Place Holder (PLH), Buffer Control Block (BCB), Buffer Subpool Header (BSPH), Buffer Header (BHD)).

This results in higher VM capacity. It also allows to further exploit Data In Memory (DIM) to save DASD I/Os and thus improve transaction response times.
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Planning Information

Customer Responsibilities

Not available.

Conversion

Not applicable.
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Security, Auditability, and Control

The security and auditability features of the announced program are multiple levels of passwords that can protect the access of data.

User management is responsible for evaluation, selection, and implementation of security features, administrative procedures, and appropriate controls in application systems and communication facilities.

Trademarks

(R), (TM), * Trademark or registered trademark of International Business Machines Corporation.

** Company, product, or service name may be a trademark or service mark of others.
 © IBM Corporation 2005.
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