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+---
+title: Maintaining a system build on ZFS
+slug: maintaining-a-system-build-on-zfs
+date: 2025-08-02
+draft: false
+authors:
+    - luc
+tags:
+    - Alpine Linux
+    - Gentoo Linux
+categories: 
+    - Maintenance
+---
+
+ZFS opens up novel methods to safely maintain a system. In this blog entry we will outline these methods in the form of an update protocol. To keep your system healthy this protocol should be executed on a weekly/monthly basis.
+
+<!-- more -->
+
+## Pre-update
+
+To be able to rollback the system after a system update, one may create a `snapshot` of the root filesystem:
+
+=== "Alpine Linux"
+
+    ``` shell-session
+    sh# zfs snapshot rpool/root/alpine@previous
+    ```
+
+=== "Gentoo Linux"
+
+    ``` shell-session
+    sh# zfs snapshot rpool/root/gentoo@previous
+    ```
+
+Furthermore, `zfs list -t snapshot` can be used to list snapshots and `zfs destroy` can be used to remove snapshots.
+
+## Update
+
+We may perform a system update:
+
+=== "Alpine Linux"
+
+    ``` shell-session
+    sh# apk upgrade
+    sh# reboot
+    ```
+
+=== "Gentoo Linux"
+
+    ``` shell-session
+    sh# emerge -auDU @world
+    sh# reboot
+    ```
+
+If the system does not behave accordingly after reboot, one may `rollback` to the previous snapshot:
+
+=== "Alpine Linux"
+
+    ``` shell-session
+    sh# zfs rollback -r rpool/root/alpine@previous
+    ```
+
+=== "Gentoo Linux"
+
+    ``` shell-session
+    sh# zfs rollback -r rpool/root/gentoo@previous
+    ```
+
+## Post-update
+
+To maintain the performance of the SSDs in the system, perform a `trim` on the ZFS-pool:
+
+``` shell-session
+sh# zpool trim --secure --wait rpool #(1)!
+```
+
+1. Some devices may not support the option `--secure`.
+
+A `scrub` on the ZFS-pool checks and repairs the data in the pool and is usually performed after a `trim`:
+
+``` shell-session
+sh# zpool scrub rpool
+```
+
+A `scrub` may take a while, its progress can be checked with:
+
+``` shell-session
+sh# zpool status rpool
+```
+
+> A ZFS scrub only repairs if `mirror` or a `zraid` mode is set in the pool.