Re: BTRFS over LVM remounts read-only

["Szalma László" <dblaci@dblaci.hu>]

Yeah, I used to do the way you wrote before, but in fact, G means 
gigabyte (1024^3), and works the same with both tools. On smaller units 
You have to watch for the rounding to extent size (4M by default).

Moreover, some could use:

btrfs fi re -2G /mount          (well, I just noticed, I accidentally 
wrote the device last time, but btrfs resize should be used on mount point.)
lvresize -L -2G /device

  :)

DBLaci

And of course, this is what should be done to prevent data loss. This 
method won't fix the original problem of course...

Thanks for your comment!

2014-01-11 20:16 keltezéssel, Roman Mamedov írta:
> On Sat, 11 Jan 2014 19:48:55 +0100
> Szalma László <dblaci@dblaci.hu> wrote:
>
>> 2014-01-11 18:10 keltezéssel, MegaBrutal írta:
>>> How can I shrink the FS to the correct size right now, ensuring that I
>>> really shrink it to the exact LV size?
>> btrfs fi re 10G /dev/mapper/vg-lv
>> lvresize -L 10G vg/lv
> That's setting yourself up for a failure if these tools happen to disagree on
> what "G" means (GB vs GiB). Maybe that's what happened here with the thread
> starter's FS?
>
> To be completely safe, I would recommend to resize the FS in two steps, leaving
> some safety margin to the partition resize first:
>
>    btrfs fi re 8G /dev/mapper/vg-lv
>    lvresize -L 10G vg/lv
>    btrfs fi re max /dev/mapper/vg-lv
>