Le 08/12/2015 16:37, Holger Hoffstätte a écrit : > On 12/08/15 16:06, Marc MERLIN wrote: >> Howdy, >> >> Why would scrub need space and why would it cancel if there isn't enough of >> it? >> (kernel 4.3) >> >> /etc/cron.daily/btrfs-scrub: >> btrfs scrub start -Bd /dev/mapper/cryptroot >> scrub device /dev/mapper/cryptroot (id 1) done >> scrub started at Mon Dec 7 01:35:08 2015 and finished after 258 seconds >> total bytes scrubbed: 130.84GiB with 0 errors >> btrfs scrub start -Bd /dev/mapper/pool1 >> ERROR: scrubbing /dev/mapper/pool1 failed for device id 1 (No space left on >> device) >> scrub device /dev/mapper/pool1 (id 1) canceled > Scrub rewrites metadata (apparently even in -r aka readonly mode), and that > can lead to temporary metadata expansion (stuff gets COWed around); it's > a bit surprising but makes sense if you think about it.
How long must I think about it until it makes sense? :-) Sorry I'm not sure why metadata is rewritten if no error is detected. I've several theories but lack information: is the fact that no error has been detected stored somewhere? is scrub using some kind of internal temporary snapshot(s) to avoid interfering with other operations? other reason I didn't think about? Lionel -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
