Marc MERLIN posted on Sat, 12 Apr 2014 13:25:42 -0700 as excerpted: > If I mount with ro,recovery, then it's actually normal speed to copy > data off it, quite weird. It seems like btrfs' background processes are > grinding the FS down to a halt, and I didn't turn on autodefrag. What happens if you simply mount it ro, without the recovery option? Is it still normal-speed or is that slow as a rw mount? Speed hasn't been an issue here, but FWIW I normally keep my rootfs ro mounted as I decided that's lower risk in the event of a system crash or power outage and I don't actually /need/ it rw most of the time (I have a dedicated /var/log, /home on an entirely separate btrfs, and the bits of /var that need to be writable in normal operation symlinked into /home/var/), only mounting the rootfs rw to update or do other system maintenance. If a ro filesystem is normal speed but rw slow, the problem must be in the write path, which is what I suspect. If a ro filesystem is slow and only a recover,ro filesystem is fast, then there's something strange going on with btrfs internals that recovery obviously bypasses. Knowing one way or the other should definitely help to pin things down. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html