[Samba] Destination share larger than windows source
Mike Kelly
mike at piratehaven.org
Fri Apr 20 12:43:47 MDT 2012
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.
Is there some other data or test results you'd like to see?
Thanks,
Mike
(:
--
--------Mike at PirateHaven.org-----------------------The_glass_is_too_big--------
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--------Mike at PirateHaven.org-----------------------The_glass_is_too_big--------
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