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 <https://restic.net/> for this since rsnapshot's developer switched to Borg and Borg doesn't do snapshots. *Problem:* I want to minimize fragmentation on the Btrfs file system, but Debian's Wiki recommends against usin <https://wiki.debian.org/Btrfs#Recommendations>g -autodefrag. The reason for this seems to be found in the Warnings section <https://wiki.debian.org/Btrfs#Warnings>: > > - 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?
