Re: btrfs dev del not transaction protected?

Eli V
2019-12-20T18:28:50Z

In general df will only ever be an approximation on btrfs filesystems
since the different profiles use different amounts of space, and it
does have bugs from time to time. If you untar a mail spool on the
filesystem the metadata usage may shoot way up when only a small
amount of additional data is needed. So on btrfs filesystems I really
just ignore df, and use btrfs filesystem usage -T almost exclusively.
The table format of -T does make it much more readable for an admin.

On Fri, Dec 20, 2019 at 1:02 PM Marc Lehmann <schmorp@schmorp.de> wrote:
>
> On Fri, Dec 20, 2019 at 12:24:05PM -0500, Remi Gauvin <remi@georgianit.com> wrote:
> > You don't need hints, the problem is right here.
> > Your Metadata is Raid 1, (which requires minimum of 2 devices,) Your
>
> Guess I found another bug - three disks with >>3tb free space, but df
> still shows 0 available bytes. Sure I can probably work around it somehow,
> but no, I refuse to accept that this is supposedly a user problem - surely
> btrfs could create more raid1 metadata with _three disks with lots of free
> space_.
>
> doom ~# df /cold1
> Filesystem Size Used Avail Use% Mounted on
> /dev/mapper/xmnt-cold15 43T 23T 0 100% /cold1
> doom ~# btrfs dev us /cold1
> /dev/mapper/xmnt-cold15, ID: 1
> Device size: 9.09TiB
> Device slack: 0.00B
> Data,single: 9.07TiB
> Metadata,RAID1: 25.46GiB
> System,RAID1: 32.00MiB
> Unallocated: 1.00MiB
>
> /dev/mapper/xmnt-cold12, ID: 2
> Device size: 7.28TiB
> Device slack: 0.00B
> Data,single: 7.25TiB
> Metadata,RAID1: 24.46GiB
> System,RAID1: 32.00MiB
> Unallocated: 1.00MiB
>
> /dev/mapper/xmnt-cold13, ID: 3
> Device size: 7.28TiB
> Device slack: 0.00B
> Data,single: 4.03TiB
> Metadata,RAID1: 5.92GiB
> Unallocated: 3.24TiB
>
> /dev/mapper/xmnt-cold14, ID: 4
> Device size: 7.28TiB
> Device slack: 0.00B
> Unallocated: 7.28TiB
>
> /dev/mapper/xmnt-cold11, ID: 5
> Device size: 7.28TiB
> Device slack: 0.00B
> Unallocated: 7.28TiB
>
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