# Does the Kernel upgrade process use A/B partitions

**URL:** <https://forums.suse.com/t/does-the-kernel-upgrade-process-use-a-b-partitions/3529>\
**Category:** RancherOS\
**Created:** [July 26, 2016, 5:18am UTC](https://forums.suse.com/t/does-the-kernel-upgrade-process-use-a-b-partitions/3529 "2016-07-26T05:18:10Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![badevguru](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/badevguru/32/1539_2.png) [@badevguru](https://forums.suse.com/u/badevguru)\
**Post date:** [July 26, 2016, 5:18am UTC](https://forums.suse.com/t/does-the-kernel-upgrade-process-use-a-b-partitions/3529/1 "2016-07-26T05:18:10Z")

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I am having a hard time finding the technical overview on the system/kernel upgrade process. Does Rancher use A/B partitions so that a failed boot can be detected and automatically reverted back to using the version prior to the upgrade attempt?

Some other wizardry?

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**Author:** ![ibuildthecloud](https://sea2.discourse-cdn.com/flex022/user_avatar/forums.suse.com/ibuildthecloud/32/8_2.png) [@ibuildthecloud](https://forums.suse.com/u/ibuildthecloud)\
**Post date:** [August 29, 2016, 10:38pm UTC](https://forums.suse.com/t/does-the-kernel-upgrade-process-use-a-b-partitions/3529/2 "2016-08-29T22:38:18Z")

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RancherOS is really just a kernel and an initrd. The upgrade process is downloading a new kernel/initrd and updating the boot loader to point to it. We don’t remove the old kernel/initrd. If there is a problem you can select the old kernel from the bootloader (grub2 by default).

Upgrades are performed with the [`sudo ros os upgrade`](http://docs.rancher.com/os/upgrading/) command.