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--- tutorial:adm:server_os_updates [2019/12/16 15:06]
fiserp [Things to consider]
+++ tutorial:adm:server_os_updates [2019/12/16 15:31]
fiserp [Solving issues]
@@ Line 69: / Line 69: @@
     - Update your test cases if necessary.
     - After about a week, check system logs to make sure all components work as expected.
+<note>For Windows OSes, the update process is roughly the same. For checking services, status of the system and system logs, use the Event Viewer and Server Manager.</note>
+==== Solving issues ====
+For maintenance actions, it is necessary to:
+  * Know how long each task will take and to measure the task duration when actually performing them.
+    * If tasks take longer than expected, you know if you can match the maintenance window or not.
+  * Know how long the whole maintenance will take (maintenance time **MT**).
+    * This is not simply a sum of task times, you should add some extra time (**ET**) to have a proper cushion.
+  * Know how long (at worst) the whole rollback will take (rollback time **RT**).
+  * Have a maintenance window that spans at least **MT**+**RT** with some extra time **ET**.
+    * You are not able to safely perform the maintenance in shorter window, there is simply not enough time. If something goes wrong, you need at most **RT** time to perform the rollback!
+    * If you do not have any **ET**, if anything goes wrong you have to perform rollback procedure. Therefore, **ET** gives you some time you can spend on solving the issue so you can carry on with updates.
+You should have a rollback procedure that can safely restore the deployment. This depends on your environment.
+Fortunately, in most cases it simply means restoring the snapshot of the virtual machine. After restoring the snapshot, you have to perform tests (with test use-cases) to confirm the rollback was performed correctly.
+Minor issues can be generally resolved with the help of ``/boot`` and ``/etc`` backups you created before updating the OS.
+If IdM installation gets hit, you can debug the configuration or restore it from the backup. Since IdM is not installed from OS packages, this usually does not happen.