[Samba] Destination share larger than windows source

[Jeremy Allison]

On Fri, Apr 20, 2012 at 11:43:47AM -0700, Mike Kelly wrote:
> On Thu, Apr 19, 2012 at 05:21:33PM -0700, Mike Kelly wrote:
> > That seems pretty strange to me, as if files are rounded up to the next
> > 1k or so.
> > 
> Actually, I made a mistake, that was output from du -sk, so the sizes
> are larger by 1MB or so!
> 
> I got some surprising results at the byte level (du -sb), which lead me
> to do a little more investigation.  Here are the files which I picked
> before, these files are not special, they happened to be near the
> beginning of the file and of differing sizes.  I've got thousands more
> with the same allocation behavior.
> 
> I used find's printf to print %s %k %S for these files.  I'll save you
> the trip to the man page:
> %s  Size in bytes
> %k  Amount of disk space in 1k blocks.
> %S  Sparseiness:  (512*st_blocks / st_size)
> 
> As stated before I'm using ext4 with 4k blocks.
> 
> All the files have the same size in bytes, but the block allocations
> differ:
> 
>           --- SA on ---   --- SA off --
>   bytes     %k    %S        %k    %S    file name
> -------   -------------   ------------- ----------------------------
> 1070035   2052  1.96372   1052  1.00674 openvpn-2.0.5-gui-1.0.3-install.exe
>  197233   1028  5.3372     200  1.03837 rest2514.exe
>  318391   1028  3.30622    316  1.01631 SCP Screens/Screenshot-1.png
>  318229   1028  3.30791    316  1.01683 SCP Screens/Screenshot-2.png
>  319245   1028  3.29738    316  1.01359 SCP Screens/Screenshot-3.png
>  324373   1028  3.24525    324  1.02282 SCP Screens/Screenshot-4.png
>  314324   1028  3.349      312  1.01643 SCP Screens/Screenshot-5.png
>  384690   1028  2.73642    380  1.01152 SCP Screens/Screenshot-6.png
>  388921   1028  2.70665    384  1.01104 SCP Screens/Screenshot-7.png
>  320041   1028  3.28918    320  1.02387 SCP Screens/Screenshot.png
>   28672   1028  36.7143     32  1.14286 SCP Screens/Thumbs.db
> 
> This is really interesting.  What you'd expect is that a normal file
> would have a sparseiness of about 1.0, while a sparse file would be less
> than 1.0.  This is what we see for the "SA off" files.  However, what we
> are seeing for the "SA on" files is super-un-sparseness, the opposite of
> sparsness.  They have more blocks allocated to them than they could
> possibly need to store their bytes.
> 
> I think we're looking at one of three possibilities:
> 1) Samba is miscalculating the allocation size.
> 2) The kernel is miscalculating the allocation size.
> 3) The ext4 file system driver is miscalculating the allocation size.

Ah. Try setting the per share parameter "allocation roundup size = 1024"
(instead of the default 1mb).

Jeremy.