On Sun, Feb 11, 2018 at 12:31:42PM +0300, Andrei Borzenkov wrote: > 11.02.2018 04:02, Hans van Kranenburg пишет: > >> - /dev/sda6 / btrfs > >> rw,relatime,ssd,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot > >> 0 0 > > > > Note that changes on atime cause writes to metadata, which means cowing > > metadata blocks and unsharing them from a previous snapshot, only when > > using the filesystem, not even when changing things (!). > > With relatime atime is updated only once after file was changed. So your > description is not entirely accurate and things should not be that > dramatic unless files are continuously being changed.
Alas, that's untrue. relatime updates happen if: * the file has been written after it was last read, or * previous atime was older than 24 hours Thus, you get at least one unshare per inode per day, which is also the most widespread frequency of both snapshotting and cronjobs. Fortunately, most uses of atime are gone, thus it's generally safe to disable it completely. Meow! -- ⢀⣴⠾⠻⢶⣦⠀ The bill with 3 years prison for mentioning Polish concentration ⣾⠁⢰⠒⠀⣿⡁ camps is back. What about KL Warschau (operating until 1956)? ⢿⡄⠘⠷⠚⠋⠀ Zgoda? Łambinowice? Most ex-German KLs? If those were "soviet ⠈⠳⣄⠀⠀⠀⠀ puppets", Bereza Kartuska? Sikorski's camps in UK (thanks Brits!)? -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
