Adminadvanced
EBS Patching Strategy: AD Utilities and Online Patching
Explain the EBS patching toolset and how R12.2's Online Patching (ADOP) minimizes downtime
EBS patching uses the AD utilities, and R12.2 changed the model substantially with online patching.
Online Patching with adop is like renovating a restaurant's kitchen in a completely separate space while the current kitchen keeps serving customers normally, and then — once the new kitchen is fully ready and tested — briefly closing for just a few minutes to swap operations over, rather than closing the whole restaurant for a multi-day renovation.
Key Concepts
1
The tools.
adpatch the traditional patch tool. Requires downtime.
adadmin maintenance: relink executables, compile flexfields,
maintain snapshots
adop R12.2 online patching
adsplice add a product to an existing installation2
Online patching uses two editions of everything.
run edition what users are on, serving traffic
patch edition a second copy of the file system and the database
objects, where the patch is applied3
Edition-Based Redefinition in the database provides the second set of code objects, and a dual file system
provides the second set of files.
4
The adop cycle.
prepare create the patch edition from the run edition
apply apply the patch to it -- the longest phase,
with users working normally throughout
finalize compile and prepare for the switch
cutover brief downtime: switch run and patch editions
cleanup drop the obsolete edition5
Where the downtime went. Applying a large patch used to mean hours of outage. Now the apply phase is
online and only cutover requires users off — typically minutes.
6
What it costs. Considerably more complexity. Two file systems, editions to track, and a cycle that must
be completed rather than abandoned.
7
An adop cycle left half-finished blocks the next one, and recovering from it is its own procedure. That is
the most common operational problem with online patching.
8
Custom code must be edition-aware. Custom objects have to follow the editioning rules, and custom files
must be placed so both editions have them.
9
Custom code written as though the system still had one file system works until the next patch cycle and
then disappears, because it existed only in the edition that was replaced.
10
The practical answer for "how do you plan a patch". Read the readme for prerequisites and conflicts,
apply it to a cloned test environment first, run the functional tests, then apply to production in a cycle
with the cutover scheduled — rather than treating adop as something that removed the need to plan.
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What the interviewer is probing.1. "What is online patching in R12.2?" Probing: the big change. Stalls: "Faster patching."
Moves up: a dual filesystem — the patch is applied to the inactive edition while users stay on the
run edition, with a short cutover.
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2. "What are the adop phases?" Probing: the specifics. Stalls: "Apply." Moves up: prepare,
apply, finalize, cutover and cleanup — cutover being the only downtime.
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3. "What must custom code respect under online patching?" Probing: the development angle.
Stalls: "Nothing." Moves up: editioning — custom objects must be registered and follow the
editioned rules, or cutover fails or leaves them stale.
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4. "How do you reduce patching risk?" Probing: the process. Stalls: "Test less." Moves up:
apply to a production clone first, keep a tested regression suite, and have a documented abort path
before cutover.