IBM OS/390 User Manual
new vendor package that runs under AIX. As guests of VM/ESA, all three can
run efficiently while sharing one processor.
run efficiently while sharing one processor.
•
You have production applications that need to be reworked to comply with
Year 2000. With VM/ESA
Year 2000. With VM/ESA
′
s Guest Support you can bring up a duplicate of
your production system, set the clock to a date and time beyond the year
2000 then perform test and application debugging without disrupting your
current production system.
2000 then perform test and application debugging without disrupting your
current production system.
•
You have production applications that need to be reworked to comply with
changes required by the European Common Currency. With VM/ESA
changes required by the European Common Currency. With VM/ESA
′
s Guest
Support you can bring up a duplicate of your production system, set the
specific elements that affect currency and/or exchange rates, then perform
test and application debugging without disrupting your current production
system.
specific elements that affect currency and/or exchange rates, then perform
test and application debugging without disrupting your current production
system.
•
If you are considering using Parallel Sysplex. VM/ESA supports guest
coupling simulation on the IBM 9672 Parallel Enterprise Servers Generation 3
and Generation 4 and on the IBM Multiprise 2000 Servers (at the appropriate
engineering change levels). VM/ESA Guest Coupling Simulation provides for
the simulation of one or more complete parallel sysplexes within a single
VM/ESA system image. The intent is to provide a pre-production testing
platform for a coupled-system installation. Other than the processors
required, there is no special hardware needed: no coupling links and no
external coupling facilities. All guest operating systems coupled within a
simulated sysplex can only be coupled (through simulated coupling links) to
coupling facilities also running as guests of the same VM/ESA system. Up to
32 virtual machines can be coupled within a simulated sysplex, with each
such virtual machine coupled to up to eight coupling facility virtual machines.
coupling simulation on the IBM 9672 Parallel Enterprise Servers Generation 3
and Generation 4 and on the IBM Multiprise 2000 Servers (at the appropriate
engineering change levels). VM/ESA Guest Coupling Simulation provides for
the simulation of one or more complete parallel sysplexes within a single
VM/ESA system image. The intent is to provide a pre-production testing
platform for a coupled-system installation. Other than the processors
required, there is no special hardware needed: no coupling links and no
external coupling facilities. All guest operating systems coupled within a
simulated sysplex can only be coupled (through simulated coupling links) to
coupling facilities also running as guests of the same VM/ESA system. Up to
32 virtual machines can be coupled within a simulated sysplex, with each
such virtual machine coupled to up to eight coupling facility virtual machines.
Performance Benefits
Guest systems may see performance improvements by exploiting VM/ESA
features. For example, both virtual disk in storage and minidisk cache allow
guests to avoid real I/Os by using data in storage and caching techniques.
features. For example, both virtual disk in storage and minidisk cache allow
guests to avoid real I/Os by using data in storage and caching techniques.
Reduced Hardware and Migration Cost
Guest systems such as OS/390, MVS, TPF, VSE, VM and others can share
devices such as channels, printers, and DASD, which VM/ESA efficiently
manages. VM/ESA adds value to such devices merely by the way it manages
them. A good example is VM/ESA
devices such as channels, printers, and DASD, which VM/ESA efficiently
manages. VM/ESA adds value to such devices merely by the way it manages
them. A good example is VM/ESA
′
s minidisk support, which allows one real disk
to function as if it were several smaller disks (such as multiple IPL-able
minidisks). VM/ESA also simulates some hardware devices (such as unit record
devices and CTC adapters).
minidisks). VM/ESA also simulates some hardware devices (such as unit record
devices and CTC adapters).
For migrating to a new release from an older VM, VSE, MVS, OS/390, or TPF,
VM/ESA gives you the ability to bring up the new system on the same physical
processor saving you the cost of a separate processor or LPAR hardware. This
new system can share the devices and resources of your existing VM/ESA
system thus eliminating the cost of separate hardware for new system migration
testing. When testing is complete switching over to your new production system
is only a matter of configuration/table changes and can be accomplished in
minutes. These technical and cost saving advantages provided by VM/ESA and
VM
VM/ESA gives you the ability to bring up the new system on the same physical
processor saving you the cost of a separate processor or LPAR hardware. This
new system can share the devices and resources of your existing VM/ESA
system thus eliminating the cost of separate hardware for new system migration
testing. When testing is complete switching over to your new production system
is only a matter of configuration/table changes and can be accomplished in
minutes. These technical and cost saving advantages provided by VM/ESA and
VM
′
s Guest Support are fundamental requirements upon which the VM/ESA
product was built and have been carefully refined over the years. This gives
Chapter 26. Test Environments
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