Fedora 19 and Btrfs
September 29, 2013
I’ve been avoiding Fedora 19, perhaps because I know it will be very much like RHEL 7 when it is released. However, I wanted to learn more about Btrfs, so Fedora 19 seemed just the thing for my test box. I booted the Fedora 19 installer, told it to use both of the hard drives in my system, and told it to auto-partition a Btrfs system. Everything else was pretty much the default.
I have two hard drives in most of my systems which I always setup in a
RAID 1 + LVM scheme. Easy management of my data and redundancy for when
the hardware gives out. Fedora 19 setup a
/boot partition on drive 1
with Ext4, a swap partition (at the end of the disk), and a middle
partition that filled the remaining space of the drive. Its was
formatted with Btrfs. The second drive had one partition formatted with
Btrfs and the two devices were part of the same Btrfs file system. The
/home mount points were in separate Btrfs subvolumes. Not bad
for the default setup, although I would have preferred the swap
partition not and the end of disk 1.
Is my data safe? Btrfs supports RAID modes for redundancy. :
# btrfs filesystem df / Data, RAID0: total=6.00GB, used=3.67GB Data: total=8.00MB, used=0.00 System, RAID1: total=8.00MB, used=4.00KB System: total=4.00MB, used=0.00 Metadata, RAID1: total=1.00GB, used=315.19MB Metadata: total=8.00MB, used=0.00
No. This looks like a default Btrfs setup, metadata defaults to RAID 1 on a multi-device setup. Data – like my music collection – does not! :
# btrfs balance start -dconvert=raid1 -mconvert=raid1 / Done, had to relocate 7 out of 7 chunks # btrfs filesystem df / Data, RAID1: total=5.00GB, used=3.67GB System, RAID1: total=32.00MB, used=4.00KB System: total=4.00MB, used=0.00 Metadata, RAID1: total=1.00GB, used=313.32MB``
Now all my data and metadata is redundant on both my disks. No crazy Fedora installer foo to setup redundancy. No reboot. I think I like this new file system…a lot.
See the balance filters that can be used with Btrfs.