On Mon, Oct 8, 2012 at 8:08 AM, Swâmi Petaramesh <sw...@petaramesh.org> wrote: > Le 08/10/2012 00:47, Goffredo Baroncelli a écrit : >> Please could you clarify if you are using the "autodefrag" options >> when you have the performance problem ? > > I use autodefrag on all volumes systematically, except on volumes that I > use for really big files that would always be defragmenting (i.e. > virtual machines, but I seldom use virtual machines, and my performance > problem is general, I don't take VMs into consideration in this respect...)
The autodefrag option is per filesystem not per subvolume. The settings of the first subvolueme is used also for the other ones. So, because you mount the same filesystem both on > /dev/VG1/BTR_POOL / btrfs subvol=UBUNTU/@,space_cache,autodefrag,compress=lzo,relatime 0 0 and > /dev/VG1/BTR_POOL /data/VBOX_HIDDEN btrfs subvol=DATA/VBOX_HIDDEN,space_cache,compress=lzo,noatime 0 0 > /dev/VG1/BTR_POOL /data/VBOX_VMS btrfs subvol=DATA/VBOX_VMS,space_cache,compress=lzo,noatime 0 0 the autodefrag option is enabled also for DATA/VBOX_HIDDEN and DATA/VBOM_VMS > >> Are you in position to to reduce the number of snapshot from hundreds >> to few ? > > I might do this as an experiment, but it would defeat one of the > prominent purposes for which I use BTRFS, and the number of snapshots > would grow immediately again, as I use the excellent OpenSuSE "snapper" > tool, that makes a snapshot every single hour... I am not suggesting that as solution, but this would help to investigate the problem. If you don't have any needs of the snapshot, you can delete it, wait that the cleaner kernel thread does its job (it could require a bit of time), then reboot the machine. If I am right the performance should goes high. I fear that both the combination of autodefrag and the high number of snapshot could be the root-cause of the the bad performance. > > Kind regards. Ciao Goffredo > -- > Swâmi Petaramesh <sw...@petaramesh.org> http://petaramesh.org PGP 9076E32E > Ne cherchez pas : Je ne suis pas sur Facebook. > -- 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
