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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 15:34] fiserp [Solving issues] |
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- Update your test cases if necessary. | - Update your test cases if necessary. | ||
- After about a week, check system logs to make sure all components work as expected. | - After about a week, check system logs to make sure all components work as expected. | ||
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+ | ==== 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. | ||
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+ | You should have a rollback procedure that can safely restore the deployment. This depends on your environment. | ||
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+ | Fortunately, | ||
+ | Minor issues can be generally resolved with the help of ``/boot`` and ``/etc`` backups you created before updating the OS. | ||
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+ | If IdM installation gets hit, you can debug the configuration or restore it from periodic backup. Since IdM is not installed from OS packages, this basically never happens. |