On Sep 11, 2014, at 1:31 PM, Duncan <1i5t5.duncan@xxxxxxx> wrote: > > I wouldn't try defragging now, but it might be worthwhile to stop the > device delete (rebooting to do so since I don't think there's a cancel) 'btrfs replace cancel' does exist, although I haven't tried it. Something isn't right though, because it's clearly neither reading nor writing at anywhere close to 1/2 the drive read throughput. I'm curious what 'iotop -d30 -o' shows (during the replace, before cancel), which should be pretty consistent by averaging 30 seconds worth of io. And then try 'iotop -d3 -o' and see if there are spikes. I'm willing to bet there's a lot of nothing going on, with occasional spikes, rather than a constant trickle. And then the question is to find out what btrfs is thinking about while nothing is reading or writing. Even though it's not 5000+ snapshots, I wonder if the balance code (and hence btrfs replace) makes extensive use of fiemap that's causing this to go catatonic. http://comments.gmane.org/gmane.comp.file-systems.btrfs/35724 Chris Murphy -- 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
