Proxmox Backup Server (PBS) has been released. It's still in beta but is already perfectly usable. After many years, it's now possible to perform incremental backups of the VMs and thanks to the qemu dirty bitmaps, backups are also fast.
The documentation is well-done and clear, so I suggest to have a look at it for all its options and features.
In short, it allows to backup any Proxmox VM or Container to a specific PBS server (which can also run Proxmox or not - it's not wise to backup on the same server where the VMs are running). It doesn't require any special file system nor setting as it splits files in chunks (so deduplication is possible and efficient) and can be stored in any supported FS.
I've been using it since the first day and it's quite efficient and reliable, I've backed up hundreds of servers and restored many of them without any problem.
Here's some hints (this post will be updated as needed):
- The first backup will be slow - at least as slow as a traditional Proxmox backup. Don't worry, it's perfectly normal.
- DO NOT TRIM THE VMs, but use the "discard" option at mount time (if Linux): trim will pass all the dirty blocks and zero them, filling the dirty bitmaps database and slowing down the next backup (even if it will not be larger).
- For the same reason, if you want to keep multiple backup servers, remember to backup to ONLY ONE PBS server and then sync it to another one. Backing up the same VMs to multiple servers will confuse the dirty bitmaps and every backup will be slower (not larger), even if it will work.
- Sometimes syncing to another server can fail and get stuck. At the moment (0.8.11-1), I found that stopping won't solve the issue and you have to restart the PBS, otherwise the task would seem to be running.
Proxmox Backup System has solved a long time problem: performing efficient, deduplicated, incremental Proxmox VM backups.