On 2015-05-27 03:37, Mosis Tembo wrote:
>
> On 05/26/2015 12:03 PM, Pavel Machek wrote:
>>> We identified the following quality metrics for this algorithm:
>>>
>>>   1) Never fails to detect out of space in the front end.
>>>   2) Always fills a volume to 100% before reporting out of space.
>>>   3) Allows rm, rmdir and truncate even when a volume is full.
>
> This is definitely nonsense. You can not rm, rmdir and truncate
> when the volume is full. You will need a free space on disk to perform
> such operations. Do you know why?
>
I assume you are referring either to Tux3 specifically or COW 
filesystems in general, because you very much _can_ do any of those on 
any of the non-COW filesystems in the Linux kernel (I know from 
experience).  Also, IIRC, it was mentioned somewhere that Tux3 keeps a 
small reserve of space on the volume for internal operations; and, I 
would assume that if that is the case, it reports the volume full when 
everything *except* that reserve of space is used, in which case rm, 
rmdir, and truncate should work fine when the volume is full.