Piotr Krawiec

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ZFS Snapshots using sanoid and syncoid

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Proxmox by default backups vms as tar archives/system images, which is not suitable for me, as I want to use zfs snapshots to ensure that I donā€™t use many system resources. Then I want to replicate those snapshots to a remote system for an offsite backup.

Installation

Follow the instructions from: https://github.com/jimsalterjrs/sanoid/blob/master/INSTALL.md

After youā€™re done see if the sanoid.timer works. This timer will execute a policy from /etc/sanoid/sanoid.conf (empty by default).

Configuration

  1. Find all the things that you want to snapshot by running:
$ zfs list
 
NAME                       USED  AVAIL  REFER  MOUNTPOINT
rpool                     45.1G   412G   104K  /rpool
rpool/ROOT                2.34G   412G    96K  /rpool/ROOT
rpool/ROOT/pve-1          2.34G   412G  2.34G  /
rpool/data                28.6G   412G    96K  /rpool/data
rpool/data/vm-100-disk-0   128K   412G    64K  -
rpool/data/vm-100-disk-1  6.08G   412G  5.96G  -
rpool/data/vm-100-disk-2  19.7G   412G  18.7G  -
rpool/data/vm-101-disk-0  2.73G   412G  2.70G  -
rpool/var-lib-vz          14.1G   412G  14.1G  /var/lib/vz
  1. Create file /etc/sanoid/sanoid.conf:
[rpool/data]
        use_template = production
        recursive = yes
        process_children_only = yes
 
#############################
# templates below this line #
#############################
 
[template_production]
        frequently = 0
        hourly = 36
        daily = 30
        monthly = 3
        yearly = 0
        autosnap = yes
        autoprune = yes

This template will backup all datasets in rpool/data but NOT the rpool/data itself. In this case I want to create snapshots of all the vm disks.

Remote replication

Our setup will consist of two machines:

  • production machine
  • remote machine, a repote machine that will store our snapshots

Remote machine configuration

Create dataset into which weā€™ll replicate the data:

zfs create data/production-machine-xxx

Remote replication uses ssh as its transport layer and we donā€™t want to give the remote machine root access.

We need to create a new user: adduser remote-backup, and give him privileges to write to it:

zfs allow -u remote-backup compression,mountpoint,create,mount,receive,rollback,destroy data/production-machine-xxx

Production machine configuration

SSH Config

Edit ~/.shh/config:

Host remote-machine:
  Hostname <ip addr>
  User remote-backup

Copy ssh key to remote machine:

ssh-copy-id remote-machine

Timer

Create /etc/systemd/system/zfs-sync.timer:

[Unit]
Description=Run syncoid daily
 
[Timer]
OnBootSec=30min
OnCalendar=*-*-* 21:00:00 Europe/Warsaw
Persistent=true
 
[Install]
WantedBy=timers.target

Example values that can be used in OnCalendar (credit: Rockibul Islam):

Explaination                          Systemd timer
Every Minute                          *-*-* *:*:00
Every 5 minutes                       *-*-* *:*/5:00
Every 15 minutes                      *-*-* *:*/15:00
Every 30 minutes                      *-*-* *:*/30:00
Every 1 hour                          *-*-* *:00:00
Every other hour                      *-*-* */2:00:00
Every 12 hour                         *-*-* */12:00:00
Between certain hours                 *-*-* 9-17:00:00
Daily                                 *-*-* 00:00:00
Every Night                           *-*-* 01:00:00
Every Night at 2am                    *-*-* 02:00:00
Every morning                         *-*-* 07:00:00
Every midnight                        *-*-* 00:00:00
Every sunday                          Sun *-*-* 00:00:00
Every friday at midnight              Fri *-*-* 00:00:00
Every weekday                         Mon...Fri *-*-* 00:00:00
Every weekend                         Sat,Sun *-*-* 00:00:00
Every 7 days                          * *-*-* 00:00:00
monthly                               * *-*-01 00:00:00
Every quarter                         * *-01,04,07,10-01 00:00:00
Every 6 months                        * *-01,07-01 00:00:00
Every year                            * *-01-01 00:00:00

Oneshot service

Create file /etc/systemd/system/zfs-sync.service:

[Unit]
Description=Send zfs snapshots to remote machine
After=network.target
 
[Service]
Type=oneshot
ExecStart=/usr/sbin/syncoid --no-privilege-elevation -r --skip-parent rpool/data remote-machine:data/production-machine-xxx
[Install]
WantedBy=default.target

Enable the timer and service:

systemctl daemon-reload; journalctl -f
systemctl enable zfs-sync.timer
systemctl enable zfs-sync.service

Start zfs-sync.service manually to sync the first snapshot:

systemctl start zfs-sync.service

You can list snapshots on the remote machine by running:

zfs list -t snapshot

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