Hi All,
First time on the mailing list.
System:
OS: Debian Buster with KDE
CPU: Intel Core i3-2100
RAM: 8 GB
OS SSD: 1 TB Crucial MX500 SSD, where /home folder is located. Formatted as ext4
Other HDD: 2 x 2 TB Toshiba L200 HDD, both used completely for Btrfs RAID1 (files and metadata) with a single subvolume, no Btrfs snapshots
Goal:
To store rotating snapshots of some folders in /home/MyUsername/ (located on SSD) on the Btrfs filesystem located on the 2 HDDs. I've chosen
Restic for this since rsnapshot's developer switched to Borg and Borg doesn't do snapshots.
Problem:
- Mounting with -o autodefrag will often duplicate
reflinked or snapshotted files when a balance is run. (TODO: is this
still current for linux-4.19.x?)
- Any
"btrfs filesystem defrag" operation can potentially duplicate reflinked
or snapshotted blocks. Files with shared extents lose their shared
reflinks, which are then duplicated with n-copies. The effect of the
lack of "snapshot aware defrag" is that volumes that make heavy use of
reflinks or snapshots will unexpectedly run out of free space. Avoid
this by minimizing the use of snapshots, and instead use deduplicating
backup software to store backups efficiently (eg: borgbackup).
Question:
Given that Restic:
- doesn't use reflinks
- uses its own snapshot system (not Btrfs')
- performs deduplication
Is it safe to use autodefrag for my use case?