Possible to preallocate files that always begin/end on stripe unit/width?

[Nathan Scott]

----- "Green Guy" <greentech3000 at gmail.com> wrote:

> ... 
> I know that XFS metadata such as the log, AG info, etc also need to be
> accounted for, but I am not sure the best way to determine how much
> space they will take.
> 
> ...
> How can I determine the correct file size and preallocate them in a
> way where they always begin/end on stripe unit/width taking the
> filesystem overhead into account?
> Note: the log needs to stay on the same fs.
> 

There's no way to make a guaranteed aligned/sized allocation, but you
can ask for a "best effort" by using the sizing information returned
from the XFS_IOC_FSGEOMETRY syscall (via xfsctl).

cheers.

-- 
Nathan