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Increasing availability of the AEpu by improving the update process

Coenen, M.H. (2019) Increasing availability of the AEpu by improving the update process.

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Abstract:Nedap needs to improve the update process of the Access Control controller to make their product highly available with only seconds of downtime each update. The current update process uses a straightforward approach which downloads the update, checks the files, stops the application, overwrite all files and reboots into the new system. After a full reboot, the access control application starts including fetching all authorisations from the server and initialising all connected hardware. This results in at least 3 minutes of downtime which can increase to 23 minutes due to the number of authorisations and the complexity of the system. This research aims to determine if the update process can be improved by implementing existing update techniques to update the kernel and filesystem within seconds and additionally add fail-safe measures to revert to the last working system in case of a failed update. The time measured as improvement indicator is the relative speed up between the downtime occurring to the access control software during an update. The downtime starts from the point in time the application is killed and stops when it is fully up and running again. Based on the insights in the old update process and two Design Space Explorations to kernel update techniques and checkpoint and restore techniques, we propose a new update process. This new process implements a second partition to store the update, uses Kexec to load and execute a new kernel directly from the running one and uses CRIU to create a checkpoint of the access control application which can be restored after a reboot. Additionally, a watchdog is implemented to reset the device in case the update fails and reboot into the last working system by using the second partition. By using the new update process, a kernel and file system update is performed with only seconds of downtime. After performing tests on a full system emulation tool a system update is performed with 13.8 seconds of downtime. Comparing this to the old update process results in a relative speed up of factor 5.6 to 11.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:54 computer science
Programme:Embedded Systems MSc (60331)
Link to this item:http://purl.utwente.nl/essays/78342
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