[PLUG] BTRFS showing full when it isn't

Tyrell Jentink tyrell at jentink.net
Thu Dec 18 19:22:34 UTC 2014


OK, I was missing the real nature of the problem; As it turns out, it
wasn't the Server OS reporting an error, but rather just the Windows
SMB/CIFS client throwing a fit.  To wit, I hadn't actually tried writing
files locally; Instead, my family had just been sending their various
backups to the server, and Windows was telling them that the server was
full, and I believed it... Then I read
https://btrfs.wiki.kernel.org/index.php/FAQ#Why_does_df_show_incorrect_free_space_for_my_RAID_volume.3F
which states that it's actually very difficult to tell how much space is
available, so if Windows asked, SAMBA wouldn't know how to answer...

Interestingly enough, sending the files from a Linux SAMBA client presented
no issue.

SO, this is PROBABLY a SAMBA Server on BTRFS bug... But it only presents
with Windows clients. At the moment, I'm just telling the family to send
files in smaller chunks, or to use SCP; Both seems to sidestep the problem,
but isn't a REAL solution...  Any ideas how to deal with THAT problem?

On Wed, Dec 17, 2014 at 9:58 PM, Tyrell Jentink <tyrell at jentink.net> wrote:
>
> I'm using BTRFS on a Fedora 20 server.  My kernel version is 3.17, and my
> BTRFS version is v3.17. My pool is composed of 2 identical 3TB drives; Some
> details on my system:
>
> #btrfs fi show
>> Label: none  uuid: 4f4b4c32-dc58-4288-a0d1-98db185dd429
>>         Total devices 2 FS bytes used 101.25GiB
>>         devid    1 size 2.73TiB used 103.03GiB path /dev/sdc
>>         devid    2 size 2.73TiB used 103.01GiB path /dev/sdd
>> Btrfs v3.17
>
>
> Which is consistent; I have the two 3TB drives, each actually reporting
> 2.73TB.  The 103 GB is interesting though, see below:
>
> #btrfs fi df .
>> Data, RAID1: total=102.00GiB, used=101.13GiB
>> Data, single: total=8.00MiB, used=0.00B
>> System, RAID1: total=8.00MiB, used=16.00KiB
>> System, single: total=4.00MiB, used=0.00B
>> Metadata, RAID1: total=1.00GiB, used=118.70MiB
>> Metadata, single: total=8.00MiB, used=0.00B
>> GlobalReserve, single: total=48.00MiB, used=0.00B
>
>
> Why am I only getting 102GB of data space?
>
> Google presented me a bunch of similar problems, but all of the ones I
> looked at were 1) running out of either meta or data space, 2) using
> devices of different sizes, or 3) needed to re-balance the pool (Normally
> resulting from either 1 or 2). My problem doesn't seem to match any of
> those scenarios, and my google-foo can't seem to get me any different
> suggestions.
>
> Are there any BTRFS gurus on this list that might be able to help?
>



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