I’m using BTRFS with satisfaction (I mentioned it in 2014 and, more recently, in the IT-Notes blog). I don’t consider it optimal for all types of loads, but it solves many problems in many situations. One of the things I use with more satisfaction is the dynamic snapshot generation function, which guarantees the possibility to have a perfect and immediate copy of a specific volume (or subvolume). When a backup is needed, for example, the use of snapshots is fundamental and having them at file system level is undoubtedly a good help.
When it comes to BTRFS volumes, however, we have additional options. There are native tools that are able to send and receive data to and from BTRFS volumes in an optimized way, taking advantage of the inherent features of the file system itself. Here is a method to automatically take snapshots and transfer them to another BTRFS volume (local or remote).
I’ve been using two interesting scripts for some time now. In the past I used snapper but I didn’t find it optimal for my use. I have therefore continued to search and found some valid alternatives, namely the combination of btrfs-snp and btrfs-sync
btrfs-snp
btrfs-snp allows to be launched specifying a path, a prefix linked to the snapshot taken, the maximum number of snapshots with that prefix to hold and a minimum time between snapshots.
For example:
root@foobar:~# /usr/local/sbin/btrfs-snp / hourly 10 3600
It will take a snapshot of /, with the term hourly as prefix (but it can be any prefix), keep a maximum of 10 snapshots and will not take any more (i.e. the program will exit without action) in less than 3600 seconds from the previous one.
You can of course combine them in this way, to have more snapshots of different types:
/usr/local/sbin/btrfs-snp / hourly 10 3600/usr/local/sbin/btrfs-snp / daily 3 86400/usr/local/sbin/btrfs-snp / weekly 1 604800
It can be launched using cron every hour (or every quarter as it will not take a new snapshot if less than 3600 seconds from the previous one have passed).
btrfs-sync
At this point, we can copy all the snapshots to another file system (local or remote) thanks to btrfs-sync.
The command can be of this type:
root@foobar:~# /usr/local/sbin/btrfs-sync -d -v /.snapshots btrfs@host:/backups/host01/
(it’s a one line command)
Obviously the destination file system must be a BTRFS volume.
I usually run the command through a script in the cron.daily, to get a daily copy of the snapshots out.
This kind of setup has already got me out of trouble several times and seems to be quite efficient.
See also
- The Double-Edged Sword of Docker: Balancing Benefits and Risks
- Make your own E-Mail server - Part 2 - Adding Webmail and More with Nextcloud
- Make your own E-Mail server - Part 1 - FreeBSD, OpenSMTPD, Rspamd and Dovecot included
- Installing Alpine Linux on a FreeBSD Jail
- How to Create a FreeBSD Jail Hosting XRDP and XFCE for Remote Desktop Access