Goffredo Baroncelli posted on Thu, 14 Nov 2013 22:21:22 +0100 as
excerpted:
> after some tests and looking at the code I discovered that the current
> mkfs.btrfs doesn't allow any raid profile other than SINGLE for data and
> meta-data when the mixed metadata/data group is enabled.
That'd be a big problem for me, here, as I run a separate sub-GiB (640
MiB) btrfs filesystem /var/log, in data+metadata raid1 mode. (The
mountpoint is actually /lg, with /var/log a symlink pointing at it.)
btrfs f sh /lg
Label: lg0238gcnx+35l0 uuid: c77a9eb8-9841-4c2b-925e-75d0a925dcc3
Total devices 2 FS bytes used 51.93MiB
devid 1 size 640.00MiB used 288.00MiB path /dev/sdc4
devid 2 size 640.00MiB used 288.00MiB path /dev/sda4
btrfs f df /lg
System, RAID1: total=32.00MiB, used=4.00KiB
Data+Metadata, RAID1: total=256.00MiB, used=51.92MiB
I've had a couple bad shutdowns, but btrfs scrub has reliably cleaned up
the resulting mess on /lg due to open logfiles, and I'd be rather unhappy
if that weren't possible.
Meanwhile, I also have two separate sub-GiB (256 MiB) /boot filesystems,
one on each (of two) SSDs, with the grub2 on each pointing at its own
/boot so a broken grub2 update won't break my ability to boot.
Those are both data+metadata dup mode:
btrfs f df /bt
System, DUP: total=8.00MiB, used=4.00KiB
System, single: total=4.00MiB, used=0.00
Data+Metadata, DUP: total=114.00MiB, used=41.38MiB
Data+Metadata, single: total=8.00MiB, used=0.00
You're saying data+metadata DUP wouldn't be possible here either, which
would make me pretty unhappy too.
Fortunately I did those mkfs.btrfs on an earlier btrfs-tools so wasn't
affected by this bug, but bug I would indeed call it, for sure!
--
Duncan - List replies preferred. No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master." Richard Stallman
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