Hi!
Why don''t you just use "du -B 4096 -sh /path/to/fs" vs.
"du -B 16384 -sh ..."?
Subtracting both results is the overhead of the one vs. the other.
But to answer your request for the formula, its:
blocks = (long)((file_size + block_size - 1) / block_size)
occupied_size = blocks * block_size
But this does not tell you the real on-disk occupation because it takes the
logical file size of the files into account. But files may be sparse or
compressed which sheds a complete different light on the problem.
I''d go with "du" command because it takes this into account.
Regards,
Kai
Sandra Schlichting <littlesandra88@gmail.com> schrieb:
> Hi all,
>
> When having a non-btrfs fs and want to migrate to btrfs, it is hard to
> know which sector size to choose in terms of disk utilization and
> speed.
>
> So I would like to make a script that scans the non-btrfs fs''s
> directory structure to find all file sizes and calculate how much
> space these would take on btrfs 4k and 16k sector size.
>
> Can anyone help me with a formulae to calculate this for a file?
>
> It doesn''t have to be exact, just enough to make a decision
between 4k and
> 16k.
>
> Best regards,
> Sandra
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