Hi Felix, On Fri, Jan 31, 2025 at 5:14 PM Felix E. Klee wrote: > > On Fri, Jan 17, 2025 at 2:25 AM Ryusuke Konishi > <konishi.ryusuke@xxxxxxxxx> wrote: > > GC runs automatically in the background based on the watermark > > conditions set in /etc/nilfs_cleanerd.conf, even if you don't run the > > nilfs-clean command. > > When I run `nilfs-clean` with options such as `--protection-period=0`, > will that change the settings of `cleanerd` until the next reboot? Or do > the options only apply to a single GC run? It only affects a single (one round) GC. Once that's done, it goes back to normal. > > If you want to ignore this ratio and force GC, use the "-m" option, > > like this: > > > > # nilfs-clean -S 20/0.1 -p 0 -m 5 > > Thanks! > > Regarding `-S 20/0.1`, that means the cleaning happens 20 times for > every 0.1 seconds? And each time `nsegments_per_clean` / > `mc_nsegments_per_clean` are cleaned? '-S 20/0.1' gives the GC pace, meaning that 20 segments are GC'd every 0.1 seconds. The numerator of the speed is the parameter equivalent to "nsegments_per_clean", which changes only during manual GC. > > LFS is a legacy method and is not common > > “not common” I understand, but why legacy? What does supersede it? Generally speaking, copy-on-write file systems such as ZFS and Btrfs are newer. The concept of LFS (Log-structured File System) itself was proposed in 1988 and implemented in UNIX in 1992. It is an old method, and I believe there are few surviving implementations today. In that sense, I used the word "legacy". In a broad sense, LFS is also a copy-on-write file system, but the difference is that it divides the storage medium into segments and performs space management (GC) on those units. > High frequency snapshotting is something I am missing from other file > systems. That may be true, but frequent snapshots are in principle possible in copy-on-write filesystems (apart from the actual support), while retroactive snapshots (the ability to turn each checkpoint into a mountable snapshot at a later time) are unique to NILFS. Regards, Ryusuke Konishi
