---
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.

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## 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.