Am 23.09.2014 um 15:38 schrieb Austin S Hemmelgarn: >> What features for example? > Well, running 'mkfs.btrfs -O list-all' with 3.16 btrfs-progs gives the > following list of features: > mixed-bg - mixed data and metadata block groups > extref - increased hard-link limit per file to 65536 > raid56 - raid56 extended format > skinny-metadata - reduced size metadata extent refs > no-holes - no explicit hole extents for files > > mixed-bg is something that you generally wouldn't want to change after > mkfs. > extref can be enabled online, and the filesystem metadata gets updated > as-needed, and dosen't provide any real performance improvement (but is > needed for some mail servers that have HUGE mail-queues) > I don't know anything about the raid56 option, but there isn't any way > to change it after mkfs. > skinyy-metadata can be changed online, and the format gets updated on > rewrite of each metadata block. This one does provide a performance > improvement (stat() in particular runs noticeably faster). You should > probably enable this if it isn't already enabled, even if you don't > recreate your filesystem. > no-holes cannot currently be changed online, and is a very recent > addition (post v3.14 btrfs-progs I believe) that provides improved > performance for sparse files (which is particularly useful if you are > doing things with fixed size virtual machine disk images). Recreating or at least "btrfstune -rx" for my rootfs would mean that I have to boot from a live medium bringing recent btrfs-progs, right? sysresccd brings btrfs-progs-3.14.2 ... that should be enough, ok? aside from that, the rootfs on my thinkpad shows these features: # ls /sys/fs/btrfs/bec7dff9-8749-4db4-9a1b-fa844cfcc36a/features/ big_metadata compress_lzo extended_iref mixed_backref So I only miss the skinny extents ... and "no-holes". Stefan -- 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
