4. Is any downtime required for the database tier? - 数据库层不需要downtime
No. In fact, the database needs to be up and running during each phase of the Online Patching cycle. However, non-Oracle E-Business Suite delivered database clients need to re-establish their database connection after the Online Patching cutover phase is performed. This includes connections from ODI Agent and Discoverer Server, as well as connection pools from Oracle SOA Suite and any other third party software connected to the Oracle E-Business Suite database.
5. How does Online Patching work on the application tier?
During Release 12.2 installation, Rapid Install will lay down two copies of the application tier file system. One of the copies will be labeled as the run file system, and the other as the patch file system. Subsequently, when a patch is applied, adop will:
1). Synchronize the contents of the run file system to the patch file system. This happens during the prepare phase.
2). Perform patching actions on the patch file system. This happens during the apply phase.
3). Finally, during the cutover phase, the adop utility restarts the application tier services. The patch file system is then promoted to be the new run file system, and the old run file system becomes the patch file system for the next patching cycle.
6. 数据库EBR ：
仅仅对数据库进行变更(不含应用变更)，使用EBR可以实现数据库不停机。 即在EBR操作完成后，还连接着数据库的应该还使用旧的版本，新连接的程序或session 在修改默认edition为new_edition后会使用到新版本。直到全部更新完成 。 EBS R12.2软件包不仅仅是数据库变更，还包括应用，不能新旧版本并行。
GRANT USE ON EDITION new_edition_name TO PUBLIC ; --- 将新版本的使用权限赋予给所有人
ALTER DATABASE DEFAULT EDITION = new_edition_name ; --- 切换默认edition为新版本
http://www.oracle.com/technetwork/issue-archive/2010/10-mar/o20asktom-098897.html
After that I’ll give an alternative ending to this example. Instead of simply “shut off the old version and start using the new
version”—a warm cutover —we’ll perform a hot rollover , whereby we’ll enable the legacy application to run concurrently
with the new application until the legacy application is no longer needed. This hot rollover capability reduces downtime from
seconds to nonexistent.
然后我会给出这个例子的另一个结尾。它不是简单地“切断旧版本并开始使用新版本”，即“温切换”，我们要进行
的是一个“热交割”，借助它我们可以使得旧版本和新版本同时并发运行，直到我们不再需要旧版本应用程序为止。
这个热交割技术把停机时间从几秒缩减到根本没有。
本文转自ITPUB博客tolywang的博客，原文链接：EBS R12.2 Online Patching(ADOP)及Oracle EBR - 2，如需转载请自行联系原博主。
