Recently replaced my cache drive and noticed the BTRFS Filesystem DF reporting the wrong size.

 

 I ran btrfs fi usage /mnt/cache and noticed that my cache drive has a large unallocated spot which is likely what is causing my issue.

 

btrfs fi usage /mnt/cache
Overall:
    Device size:                 465.76GiB
    Device allocated:            171.03GiB
    Device unallocated:          294.73GiB
    Device missing:                  0.00B
    Used:                        167.42GiB
    Free (estimated):            297.08GiB      (min: 297.08GiB)
    Data ratio:                       1.00
    Metadata ratio:                   1.00
    Global reserve:              260.03MiB      (used: 0.00B)

Data,single: Size:168.00GiB, Used:165.65GiB
   /dev/nvme0n1p1        168.00GiB

Metadata,single: Size:3.00GiB, Used:1.76GiB
   /dev/nvme0n1p1          3.00GiB

System,single: Size:32.00MiB, Used:48.00KiB
   /dev/nvme0n1p1         32.00MiB

Unallocated:
   /dev/nvme0n1p1        294.73GiB
 

I looked on the googles and found that there is a btrfs filesystem resize max command that looks like it could correct the issue, but I would like to know if are any requirements to do this since it would be expanding the volume.

 

I'm assuming the best practice would be to stop the array, backup the data, then do the command: btrfs filesystem resize max /mnt/cache and then bobs your uncle.

 

Just wanted some clarification in case I need to format the cache drive instead.

 

Thanks in advance!

smalls-diagnostics-20190731-2102.zip

Edited August 1, 20196 yr by GroxyPod

df is unreliable with btrfs, unallocated space is normal with btrfs, the filesystem allocates chunks as needed, the GUI will report the correct used/free size.

1 hour ago, johnnie.black said:

df is unreliable with btrfs, unallocated space is normal with btrfs, the filesystem allocates chunks as needed, the GUI will report the correct used/free size.

 

Thanks johnnie.black!