Good day all,
I've been happily using BTRFS for awhile on my home NAS server. A few
months ago I switched from an underlying MDADM raid with BTRFS ontop,
to a native BTRFS w/ RAID6 Profile. While I normally have 8 drives, I
am currently in process of RMA'ing a bad drive so you will see only 7
in my current setup.
root@maizy /media/Linux # uname -a
Linux maizy 4.0.0-trunk-amd64 #1 SMP Debian 4.0-1~exp1 (2015-04-21)
x86_64 GNU/Linux
root@maizy /media/Linux # btrfs --version
btrfs-progs v4.0
root@maizy /media/Linux # btrfs fi show .
Label: 'maizy:media' uuid: e878553f-888f-425d-bf75-97ffeb6e0d0d
Total devices 7 FS bytes used 11.02TiB
devid 1 size 5.46TiB used 2.21TiB path /dev/sdb
devid 2 size 5.46TiB used 2.21TiB path /dev/sdc
devid 3 size 5.46TiB used 2.21TiB path /dev/sdd
devid 4 size 5.46TiB used 2.21TiB path /dev/sde
devid 6 size 5.46TiB used 2.21TiB path /dev/sdf
devid 7 size 5.46TiB used 2.21TiB path /dev/sdh
devid 8 size 5.46TiB used 2.21TiB path /dev/sdg
btrfs-progs v4.0
root@maizy /media/Linux # btrfs fi df .
Data, single: total=8.00MiB, used=0.00B
Data, RAID6: total=11.03TiB, used=11.01TiB
System, single: total=4.00MiB, used=0.00B
System, RAID6: total=80.00MiB, used=720.00KiB
Metadata, single: total=8.00MiB, used=0.00B
Metadata, RAID6: total=13.20GiB, used=11.64GiB
GlobalReserve, single: total=512.00MiB, used=0.00B
The problem(s) I'm seeing all come from a root problem: scrub takes
over a week to finish. Because scrub takes so long I have tried to
setup a cancel and resume operation until it finishes. I've noted
that after a resume, a btrfs scrub will do some "seeming" arbitrary
amount more of scrubbing then exit clean. It doesn't seem to ever
finish whats actually leftover to scrub. I don't know if this is by
design or if I'm missing something.
A point that I see often is that scrubbing daily or weekly is
recommended, but I can't do that as a single scrub takes over a week.
It doesn't seem logical to assume that my FS should be in constant
scrub (starting another as soon as it finishes). I am under the
assumption that RAID improvements to BTRFS will speed this up over
time, however cancel and resume seems broken to me. I didn't see a
bug open or closed regarding this on bugzilla so I wanted to open a
dialog here before opening one myself (I have to remember my bugzilla
accnt info).
Regards all,
Izzy Condie
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