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Data Compression Program for VM/ESA
Description of
Data Compression Program for VM/ESA
Highlights of VM Data Compression
Major Advantages of VM Data Compression
Business Value of VM Data Compression
System Considerations
for VM Data Compression
VM Data Compression Program (PID # 5697-235)
Data compression has long been recognized as an effective
technique to reduce data storage requirements
and to reduce the load on the I/O subsystem. While compression products
have long been avialable for various operationg environments and data
types, compression for CMS minidisk file data has never been supported,
until now. With the availablility of DATA COMPRESSION PROGRAM for
VM/ESA, data compression is now supported for CMS minidisks.
DATA COMPRESSION PROGRAM for VM/ESA enables VM customers to automatially
and transparently compress and expand CMS minidisk file data. This
capability can help reduce DASD utilization, load on the I/O subsystem,
and staff time spent managing minidisk space and "disk full"
conditions.
VM DATA COMPRESSION PROGRAM performs compression and expansion
dynamically as files are being created and updated or read by
application programs. Because data compression is automatic and
Because data compression is automatic and transparent, no modifications
are required to application programs.
Data compression is controlled throught the use of compression rules
stored in a rules database managed by a rules server virtual machine.
Compression activity is reported in compression statistics records
stored in a statistics database managed by a statistics server
virtual machine.
- Reduces DASD requirements for CMS minidisk files
- Provides automatic, transparent compression and expansion of
data in CMS minidisk files.
- Reduces system I/O load and improves storage utilization
for CMS minidisk caching.
- Exploits the S/390 hardware compression facility
- Allows system administrators and CMS users to specify
criteria to control data compresssion.
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Provides five compression techniques, including a
dynamic data analyzer that selects the compression
technique that yields the best compression performance
- Includes a Trial Utility program and a Compression Simulation
mode which allows system administrators
to evaluate the benefits of data compression without
actually writing compressed data in CMS files
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Requires no changes to application programs
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Compression and expansion of minidisk files is automatic and transparent,
requiring no application modifications.
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Compressed files occupy fewer blocks of disk space and
may require fewer I/O's to read, reducing access time
and load on the I/O subsystem.
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Provides commands which allow system administrators
and general users to control data compression at the
CMS file level.
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Provides commands which allow system administrators
and general users to view statistics on data compression to determine
compression benefits.
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Provides five compression algorithms, allowing the
installation to choose the method which produces the
best results with the least consumption of system resources.
- Exploits the S/390 hardware assisted compression feature
on ES/9000 series processors (if available).
- Reduces DASD costs
- Improves data access time, improving productivity
- Saves time spent managing minidisk space allocations
Software
The following minimum version or release levels are required
for installing DATA COMPRESSION PROGRAM for VM/ESA.
Follow-on versions or releases of these products can be used unless
otherwise stated.
Required software
VM/ESA Version 2 Release 1 (5653-030) with PTF UM27737
Optional software
IBM Library for SAA RESS/370 Release 2 or later (5695-014)
DATA COMPRESSION PROGRAM for VM/ESA is written in
Assembler and compiled REXX.
IBM Library for SAA REXX/370 Release 2 (or later) is required to take
advantage of the performance benefits of compiled REXX.
The Alternate Library for SAA REXX/370 is distributed with the product
for customers who cannot take advantage of compiled REXX programs.
Hardware
Data Compression Program for VM/ESA requires
the same machine configuration as VM/ESA Version 2, Release 1.
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