Sanoid / Syncoid

Tools

https://github.com/jimsalterjrs/sanoid

sanoid – a policy-driven snapshot management tool for ZFS filesystems.

Installation (Ubuntu)

2021-11-28: It seems Ubuntu packages are badly lagging behind so git it and generate the .deb package is better.

https://github.com/jimsalterjrs/sanoid/blob/master/INSTALL.md#debianubuntu

sudo cp /usr/share/doc/sanoid/sanoid.conf.example /etc/sanoid/sanoid.conf

Configuration

We keep the already existing templates.

One key point is that pruning is not done by syncoid but only and always by sanoid. This means sanoid has to be run on the backup datasets as well, but without creating snapshots, only pruning (as set in the template).

Also, the template is called template_something and only something must be use with use_template.

[SAN200/projects]
        use_template = production
        recursive = yes
        process_children_only = yes

[BACKUP/SAN200/projects]
        use_template = backup
        recursive = yes
        process_children_only = yes

https://github.com/jimsalterjrs/sanoid/wiki/Sanoid

CAVEAT: post_snapshot_script cannot be used with syncoid

Especially with recursive = yes. This is because there cannot be two zfs send and receive at the same time on the same dataset (details ?).

And, sanoid does not wait for the script completion before continuing. This mean that should the syncoid process take a bit too much time, a new one will be spawned. And for reasons unknown to me yet, a new syncoid process will cancel the previous one (instead of just leaving).

As some of the spawned syncoid will produce errors, the entire sanoid process will fail.

So… no way… this does not work and has to be done independently, it seems.

The good news is that the SystemD service of Type= oneshot can have several Execstart= lines.

syncoid – a tool to facilitates the asynchronous incremental replication of ZFS filesystems.

https://github.com/jimsalterjrs/sanoid/wiki/Syncoid

sudo /usr/sbin/syncoid --recursive --skip-parent SAN200/projects BACKUP/SAN200/projects
$ /usr/sbin/syncoid --identifier=externalUSB storage/documents USBdrive/documents

This will create the following snapshot on both sender and receiver:

{destination_dataset}@syncoid_{identifier}_{hostname}_{extended_date}
USBdrive/documents@syncoid_externalUSB_mycomputer_2021-12-12:12:18:09-GMT01:00

SystemD service and timer

$ more /etc/systemd/system/syncoid.service 
[Unit]
Description=Runs syncoid
Wants=syncoid.timer

[Service]
Type=oneshot
ExecStart=/usr/sbin/syncoid --recursive --skip-parent SAN200/projects BACKUP/SAN200/projects
ExecStart=/usr/sbin/syncoid --recursive --skip-parent SAN300/projects BACKUP/SAN300/projects

[Install]
WantedBy=multi-user.target
$ more /etc/systemd/system/syncoid.timer 
[Unit]
Description=Runs syncoid
Requires=syncoid.service

[Timer]
Unit=syncoid.service
OnCalendar=*-*-* *:10:00

[Install]
WantedBy=timers.target
sudo systemctl daemon-reload
sudo systemctl restart syncoid.timer
systemctl list-timers
man systemd.unit
man systemd.service
man systemd.time