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djmwj1

Member

Registered: 2013-10-04

Posts: 32

[SOLVED] BTRFS - show vs usage discrepancy?

Hello All,
I have come across an interesting discrepancy that I hope someone could help me understand.
BTRFS in a RAID1 setup is showing two different usage values depending on the command used.
btrfs filesytem show
   - indicates I have used 354.07 GiB for total devices but then also shows both raid 1 drives as using their full size (465.76GiB). How can this be?

btrfs filesystem usage
   - indicates i have used 354.07 GiB in agreement with used of the total from the show command and shows the correct free space.

So why do the individual devices report as full when using the show command even thought the total used is much less?  I assume I am misinterpreting this or is it a bug?

Thanks!

[xxxxxxxxxxxxxxxxxxxxx]$ sudo btrfs filesystem show / 
Label: 'root_pool'  uuid: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
	Total devices 2 FS bytes used 354.07GiB
	devid    1 size 465.76GiB used 465.76GiB path /dev/mapper/crypt_root1
	devid    2 size 465.76GiB used 465.76GiB path /dev/mapper/crypt_root2

[xxxxxxxxxxxxxxxxxxxxx]$ sudo btrfs filesystem usage /
Overall:
    Device size:		 931.52GiB
    Device allocated:		 931.52GiB
    Device unallocated:		   2.01MiB
    Device missing:		     0.00B
    Used:			 708.14GiB
    Free (estimated):		 108.75GiB	(min: 108.75GiB)
    Free (statfs, df):		 108.75GiB
    Data ratio:			      2.00
    Metadata ratio:		      2.00
    Global reserve:		 392.80MiB	(used: 0.00B)
    Multiple profiles:		        no

Data,RAID1: Size:461.75GiB, Used:353.00GiB (76.45%)
   /dev/mapper/crypt_root1	 461.75GiB
   /dev/mapper/crypt_root2	 461.75GiB

Metadata,RAID1: Size:4.00GiB, Used:1.07GiB (26.79%)
   /dev/mapper/crypt_root1	   4.00GiB
   /dev/mapper/crypt_root2	   4.00GiB

System,RAID1: Size:8.00MiB, Used:80.00KiB (0.98%)
   /dev/mapper/crypt_root1	   8.00MiB
   /dev/mapper/crypt_root2	   8.00MiB

Unallocated:
   /dev/mapper/crypt_root1	   1.00MiB
   /dev/mapper/crypt_root2	   1.00MiB

Last edited by djmwj1 (2021-12-17 15:15:29)

djmwj1

Member

Registered: 2013-10-04

Posts: 32

Re: [SOLVED] BTRFS - show vs usage discrepancy?

For posterity. It turns out that the show command is showing the allocated space for each device as well as the total actually used. So in the end no problem.
https://btrfs.wiki.kernel.org/index.php … _I_have.3F