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I've read that before. Basically correct, but a btrfs snapshot is as good as any other in-system backup. Btrfs can bring a high level of security against data loss for home users. With some additional work, the external backup for btrfs can also be achieved. Then backup 3-2-1 with btrfs is easily possible
Btrfs with RAID0 and readonly snapshots by snapper are like a backup of the original files housed in the same system. It protects against:
- minor problems, like accidentally deleting a file
- delete an entire file tree (e.g. /home/hans/* )
- from unintentionally changing file permissions of many files
- unintentionally modified files
Running btrfs with RAID1 on at least 2 different devices is as good as a local backup.
This also protects against:
- Failure of a complete device
- Corruption of the file system on a device
- Loss of partition table on a device
- overwrite a device with dd ;-)
If the snapshots are also backed up on an external disk, this is another REAL external backup. At best, the external disk should only be connected to the computer for a short time. This also protects against:
- Complete failure of the computer
- Loss of past backups up to capacity of external disk
- Targeted deletion of the internal backups (e.g. by Mallware)
Btrfs then corresponds to 3-2-1 Backup (Near CDP)
Simple external backup of a complete (btrfs) subvolume
- Back up all snapshots
- Differential backup of each snapshot (fast). If the backup is repeated after a few days/weeks/months
- As little space consumption on the backup medium as possible
- The backup medium can be used for backups of different computers
- Command line program without GUI
- KISS
- with GUI -g clear representation of snapshots and existing backups
- GUI controlled deletion of outdated backups
- GUI controlled pruning of backups
- Automatic management of backups by age
- Automatically delete old backups when there is not enough space
- Backup of the current state of a subvolume
- The backup strategy is already defined in snapper~~/Timeshift~~, and is involved here
- The backup is compressed, but at the same time all snapshots in the backup are always fully read-only accessible
- Java 17 or newer on the computer
- Recommended: pv installed
- BTRFS both on the computer (recommended as RAID 1 with 2 devices) and on the backup medium (single)
- snapper layout of the snapshots (the program may also work with other layouts)
- The snapshots must be readonly otherwise btrfs cannot transfer them.
- Recommended: external backup medium e.g. USB3 hard drive
- Recommended: your own bash script to start the backup easily
The Java program BackSnap backs up ALL snapshots from a specified directory to another directory on a backup medium. To do this, it uses btrfs send and btrfs receive.
The 1st passed parameter points to the SOURCE path where the snapshots are reachable by Snapper. Snapper creates all snapshots in directories with ascending numbering. The actual snapshot there is simply called "snapshot".
- /
- /home
- /.snapshots (alternative)
- /home/.snapshots (alternative)
The 2nd parameter points to the DESTINATION path at which the snapshots are to be saved. To do this, the backup medium must be mounted before the program is called. A backup subvolume named /@BackSnap and a directory with individual Names for each subvolume of each PC are suggested. The path to this mounted directory will be specified as the TARGET path for the backup.
- /mnt/BackSnap/manjaro21
- /mnt/BackSnap/manjaro21.home
Backsnap goes through all the directories in the source path in ascending time order and checks if that respective directory already exists at the destination. If not, the snapshot will be saved there.
If possible, a previous snapshot is used as "parent".
Each time the program is called, all snapshots of ONE subvolume can be backed up, which corresponds to ONE configuration of Snapper.