If you ever worked for SAP upgrade project
you probably already came across to this term – shadow system or instance and system
switch. What is that? Let me first introduce background of upgrades. Basically
by upgrade we want to get the newest functions that provider offers in its software
product that we are currently using. For sure we want to get this done without
an interruption to existing, running system. In reality there is always some interruption.
We are just trying to minimize it as much as possible. So does the SAP. The
background of shadow system is to minimize system downtime during the upgrade.
Shadow system is basically
copy of system that is going to be upgraded. This copies system is a bit
limited to original one. It has only technical repository (SAP Basis objects) of
objects and you cannot run your business processes on it. More over technical repository is upgraded
into version of final release of to be upgraded system. Technically speaking it
is used for modification adjustments (famous transactions SPAU and SPDD) and
activation of objects. All the support
packages and add-ons are imported into this instance as well. By them you
get you system to the higher release. Let me mention also that shadow system
run in the same database as its original system. They are running in parallel.
During preparation of shadow
instance you are still running your original SAP system where all the business
processes are being executed normally. At the moment when shadow instance is prepared
we do its switch from shadow to original system. This is called system switch
when you kind of “exchange” original system with shadow one. By that time
shadow system becomes upgraded system.
By using this approach you
can minimize downtime of your production system and also you do not have to
have additional hardware resource for creation of shadow instance as it runs in
the same database and application server as original system.
Notice that a matter of
SAP system is very complex all the information provided can serve as very brief
introduction into this topic. I wish you a lot of successful upgrade projects.
More
on this topic:
Different
SAP upgrade tools
2 comments:
good
that was very helpful..thats exactly what my senior told me about shadow instance today :)
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