Re: Btrfs best practices: defrag?
Hello, On Wed, Jan 26, 2022 at 08:38:41PM +, piorunz wrote: > My current fstab mounting: > > noatime,space_cache=v2,compress-force=zstd:3 0 2 > > Will autodefrag break COW files? Like I copy paste a file and I save > space, but defrag with destroy this space saving? Yes, I believe so. That is, if you have files sharing extents (like if you de-duplicated them or did a "cp --reflink=always") and defrag touches those files, it will undo the extent sharing. > Also, will autodefrag compress files automatically, as mount option > enforces (compress-force=zstd:3)? Yes. > Any suggestions welcome. If you're not relying on extent sharing then I'd think that automated defrag is okay. Cheers, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting
Re: Btrfs best practices: defrag?
I'd like to add question to this topic. Is it safe & recommended to run autodefrag mount option in fstab? I am considering two machines here, normal desktop which has Btrfs as /home, and server with VM and other databases also btrfs /home. Both Btrfs RAID10 types. Both are heavily fragmented. I never defragmented them, in fact. Running manual defrag on server machine, like: sudo btrfs filesystem defrag -v -t4G -r /home takes ages and can cause 120 second timeout kernel error in dmesg due to service timeouts. I prefer to autodefrag gradually, overtime, mount option seems to be good for that. My current fstab mounting: noatime,space_cache=v2,compress-force=zstd:3 0 2 Will autodefrag break COW files? Like I copy paste a file and I save space, but defrag with destroy this space saving? Also, will autodefrag compress files automatically, as mount option enforces (compress-force=zstd:3)? Any suggestions welcome. -- With kindest regards, Piotr. ⢀⣴⠾⠻⢶⣦⠀ ⣾⠁⢠⠒⠀⣿⡁ Debian - The universal operating system ⢿⡄⠘⠷⠚⠋⠀ https://www.debian.org/ ⠈⠳⣄
