Personal_Website/content/snippets/zfs-automatic-snapshots.md

title	date	tags	draft	icon
ZFS Automatic Snapshotting	2022-10-31T17:56:35Z	archlinux linux zfs	true	backup

Goal

Solution

Creating snapshots

{{< codegroup >}} Systemd-timer

[Unit]
Description=Create a daily ZFS snapshot for %I

[Timer]
OnCalendar=daily
Persistent=true

[Install]
WantedBy=timers.target

Systemd-service

[Unit]
Description=Create a ZFS snapshot for %I
DefaultDependencies=no

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/usr/bin/bash -c '/usr/bin/zfs snapshot "%I@daily-$(date "+%%Y-%%m-%%d")"'

{{< /codegroup >}}

Cleaning up snapshots

Get all older snapshots {{< codegroup >}} bash

zfs list -t snapshot -o name | \
perl -e '
my $one_week_ago = `date --date "7 days ago" "+%s"`;
my %snapshots = ();

for (<>) {
    if (my ($dataset, $snapshot, $date) = /([\w\/]+)@(daily-(\d+\-\d+\-\d+))/) {
        if (`date --date "$date" "+%s"` < $one_week_ago) {
            push(@{$snapshots{$dataset}}, $snapshot);
        }
    }
}

while(my ($key, $value) = each %snapshots) {
    print "$key@", join(",", @{$value}), "\n";
}'

{{< /codegroup >}}