Re: Minimum size of Btrfs volume ?

[A L <mail@lechevalier.se>]

---- From: Bill Dietrich <bill@billdietrich.me> -- Sent: 2020-08-23 - 15:26 ----

> [Noob here, sorry if I'm doing anything wrong.]
> 
> What is the minimum size of a simple single-disk Btrfs volume,
> and where is it documented ?  I can't find that info.
> 
> I'm told the minimum size is about 109 MB (114294784 bytes).
> True ?  Is there any way to get around that, at mkfs-time ?
> I'd like to use Btrfs inside a VeraCrypt container, and that's
> a fairly big minimum size for that use.
> 
> I'm using Btrfs on Ubuntu GNOME 20.04 desktop.
> 
> Thanks,
> 
> Bill Dietrich
> bill@billdietrich.me
> 
> 
> 
> -- Email domain proudly hosted at https://migadu.com

I'm not sure what minium limit is, but you can try using mkfs.btrfs --mixed. This worked with a 50MiB fs on btrfs-progs 5.7:

# btrfs fi us /mnt/loop
Overall:
    Device size:		  50.00MiB
    Device allocated:		   9.00MiB
    Device unallocated:		  41.00MiB
    Device missing:		     0.00B
    Used:			  32.00KiB
    Free (estimated):		  45.16MiB	(min: 45.16MiB)
    Data ratio:			      1.00
    Metadata ratio:		      1.00
    Global reserve:		 832.00KiB	(used: 0.00B)
    Multiple profiles:		        no

Data+Metadata,single: Size:5.00MiB, Used:28.00KiB (0.55%)
   /dev/loop0	   5.00MiB

System,single: Size:4.00MiB, Used:4.00KiB (0.10%)
   /dev/loop0	   4.00MiB

Unallocated:
   /dev/loop0	  41.00MiB