What is this?

This is a collection of scripts for the use of making backups on a zfs.

How to use this

• Clone this repo or download it somehow
• Create your backup.cfg (there is an example backup.cfg.def contained in this repo)
• Afterwards just execute the backup.bash script (as root) and the backup will be made

The variables

variable name	description
BACKUP_POOL	the name of the pool on which the backup is stored
BACKUP_DS_NAMES	a list of datasets on which the different backups are stored (for more see below)
SNAPSHOT_NAME	the name of the snapshot which then is transferred to the backup device
ARRAY_SET	a list of all datasets that should be backupped (full path starting from the pool is required)

BACKUP_DS_NAMES

The amount of items in this list descide how many backups are left on the backup-pool (e.g. "bak1" "bak2" means that there will always be two backups, the previous one and the current one)

Prerequisites

To successfully run the backup.bash, the datasets specified as backupDsNames all have to exist. In addition, on each of these sets there have to be datasets with the same name/path as the ones you want to back up.

Example: BACKUP_POOL=backup ; BACKUP_DS_NAMES=("bak1" "bak2") ; ARRAY_SET=("data/daten data/home") then the Datasets backup/bak1, backup/bak2, backup/bak1/daten, backup/bak1/home, backup/bak2/daten and backup/bak2/home have to exist.

Hint: By running backup.bash with the -n flag, the script automatically detects missing datasets (and snapshots) which are needed before creating the backup and creates them.

Encryption

In case you're using encypted datasets, these need to be mounted before running zfs send | zfs recv. In case an encrypted dataset is not mounted, the backup.bash script will try to mount it (and you will need to provide the passphrase for the decryption).

Progress

Just a small snippet of lua (using the date library) for calculating when the replication is finished (or when it should be finished)

function foo(sent)
    now = date()
    -- insert the start time/date here (if you do this later, you can check the
    -- change date of `stat.txt` and/or the timestamp should also be included in
    -- the console output)
    start = date(2024, 3, 4, 17, 46, 8)
    total_s = (now - start):spanseconds() * (379 / sent)

    return start:copy():addseconds(total_s)
end

Credits

A huge thank you to Galatheas for pointing me to zfs and the basic framework of the backup.bash script originates from him too