Re: Unexpected ENOSPC on a SSD-drive after day of uptime, kernel?2.6.32-rc5

[Josef Bacik <josef@redhat.com>]

On Thu, Nov 05, 2009 at 08:55:12PM +0000, miyamoto moesasji wrote:
> 
> > Hmm looks like quite a bit of your fs got taken up for metadata.  Perhaps try
> > running btrfsctl -b /usr and see if that frees up some space for you. 
> Thanks,
> 
> 1) The btrfsctl does not have the -b option on my system, is that an option
> that only is only enabled with the debug-utilities?
> 

Sorry I always get that wrong, its btrfs-vol -b.

> 2) I would find it surprising if it is meta-data just looking at the numbers.
> Below is the output of btrfs-show for all partitions with btrfs.
> 
> Label: none  uuid: a12ac0e9-cbea-4acf-bb26-181146940714
>         Total devices 1 FS bytes used 89.53MB
>         devid    1 size 8.00GB used 5.63GB path /dev/sda5
> 
> Label: none  uuid: 59997df9-c5a3-431f-b0a0-95b9e3b1afff
>         Total devices 1 FS bytes used 150.14MB
>         devid    1 size 4.00GB used 2.04GB path /dev/sda2
> 
> Label: none  uuid: 558766bb-5e0d-48dd-9a13-7117f3047710
>         Total devices 1 FS bytes used 180.94MB
>         devid    1 size 20.00GB used 5.04GB path /dev/sda6
> 
> Label: none  uuid: 0a89100d-096d-4c67-b3c7-745c9b7c3dc5
>         Total devices 1 FS bytes used 10.60GB
>         devid    1 size 20.00GB used 20.00GB path /dev/sda3
> 
> Label: none  uuid: 3cac73e5-e998-49bf-b8ee-ba953c92bc0b
>         Total devices 1 FS bytes used 28.00KB
>         devid    1 size 32.00GB used 2.04GB path /dev/sdb2
> 
> As an example the /var (dev/sda5) has only 89MB in use, while btrfs-show
> demonstrates 5.63GB being used of the 8GB. It almost looks as if files that are
> overwritten don't get removed from the space being in use. 
> 

The used part is how much of the volume is allocated into chunks.  So when it
says 5.63 gb is being used, that means that 5.63 gbs of the volume has been
carved up into data/metadata chunks.  I hope to at some point make one of our
utilities tell you how much of that is for data and how much of that is
metadata.  Thanks,

Josef