Hi Chris, After our quick chat, I gave it a shot on 3.19.6, and things are better than last time I tried.
legolas:/var/local/nobck/VirtualBox VMs# lsattr Win7/ ---------------C Win7/Logs ---------------C Win7/Snapshots ---------------C Win7/Win7.vdi ---------------C Win7/Win7.png ---------------C Win7/autotune1.png ---------------C Win7/new_autotune2.png ---------------C Win7/Win7.vbox-prev ---------------C Win7/Win7.vbox But I have snapshots of that subvolume, so obviously that gets in the way of disabling COW. I had a look, and I have 100K fragments. That took 10mn to figure out: legolas:/var/local/nobck/VirtualBox VMs/Win7# filefrag Win7.vdi Win7.vdi: 104306 extents found This first filefrag run took about 10mn to count all the fragments on my SSD. That feels a bit slow, but maybe the userland tool is doing things in suboptimal ways. Defrag actually worked (mostly) and wasn't too slow. It used to take hours not to finish, and now it worked in 3mn: legolas:/var/local/nobck/VirtualBox VMs/Win7# time btrfs fi defrag Win7.vdi real 3m43.807s user 0m0.000s sys 0m44.044s This is defintely better than before. Note that it's not fully defragged, but close enough. Each subsequent run, filefrag is faster, and defrag is still faster than filefrag: legolas:/var/local/nobck/VirtualBox VMs/Win7# time filefrag Win7.vdi Win7.vdi: 11428 extents found real 2m42.090s user 0m0.000s sys 2m37.308s legolas:/var/local/nobck/VirtualBox VMs/Win7# time btrfs fi defrag Win7.vdi real 0m7.483s user 0m0.000s sys 0m2.672s legolas:/var/local/nobck/VirtualBox VMs/Win7# time filefrag Win7.vdi Win7.vdi: 11132 extents found real 0m22.525s user 0m0.000s sys 0m22.264s It's a bit unexpected that I still have 10k fragments after 2 defrag runs, but it's better than 100k :) Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/ | PGP 1024R/763BE901 -- 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