On Thu, Jun 2, 2011 at 5:20 AM, John Drescher <drescherjm AT gmail DOT com> 
wrote:
> On Thu, Jun 2, 2011 at 5:10 AM, Ralf Gross <Ralf-Lists AT ralfgross DOT de> 
> wrote:
>> John Drescher schrieb:
>>> On Thu, Jun 2, 2011 at 4:05 AM, Ralf Gross <Ralf-Lists AT ralfgross DOT de> 
>>> wrote:
>>> > Rickifer Barros schrieb:
>>> >> Yes John...
>>> >>
>>> >> Now, I think that I understood perfectly and I have tested it too.
>>> >>
>>> >> VolumeToCatalog = Compares the files in a Storage Volume with the 
>>> >> Catalog;
>>> >
>>> >
>>> > VolumeToCatalog does not read the file content and compares it, it just
>>> > reads the attributs and compares them (md5sum....).
>>> >
>>> > quote:
>>> > http://www.bacula.org/en/dev-manual/main/main/Configuring_Director.html
>>> >
>>> > VolumeToCatalog
>>> >    This level causes Bacula to read the file attribute data written
>>> > to the Volume from the last Job. The file attribute data are compared
>>> > to the values saved in the Catalog database and any differences are
>>> > reported. This is similar to the Catalog level except that instead of
>>> > comparing the disk file attributes to the catalog database, the
>>> > attribute data written to the Volume is read and compared to the
>>> > catalog database.
>>>
>>> This part to me says it does compare the data on the volume with the
>>> hash MD5/SHA1 that is stored in the database.
>>
>>
>> I always thought that a VolumeToCatalog job would not read the
>> data written to the volume and calculate the md5sum again. Instead it
>> would just read the file attributes that were written to the volume and
>> compare that with the attributes in the catalog.
>>
>> At least the volume format described in developers.pdf suggest that the 
>> md5sum
>> information is part of the data stream.
>>
>> 10.7 Record Header
>>
>> #define STREAM_UNIX_ATTRIBUTES 1 /* Generic Unix attributes */
>> #define STREAM_FILE_DATA 2 /* Standard uncompressed data */
>> #define STREAM_MD5_SIGNATURE 3 /* MD5 signature for the file */
>> #define STREAM_GZIP_DATA 4 /* GZip compressed file data */
>> /* Extended Unix attributes with Win32 Extended data. Deprecated. */
>> #define STREAM_UNIX_ATTRIBUTES_EX 5 /* Extended Unix attr for Win32 EX */
>> #define STREAM_SPARSE_DATA 6 /* Sparse data stream */
>> #define STREAM_SPARSE_GZIP_DATA 7
>> #define STREAM_PROGRAM_NAMES 8 /* program names for program data */
>> #define STREAM_PROGRAM_DATA 9 /* Data needing program */
>> #define STREAM_SHA1_SIGNATURE 10 /* SHA1 signature for the file */
>> #define STREAM_WIN32_DATA 11 /* Win32 BackupRead data */
>> #define STREAM_WIN32_GZIP_DATA 12 /* Gzipped Win32 BackupRead data */
>> #define STREAM_MACOS_FORK_DATA 13 /* Mac resource fork */
>> #define STREAM_HFSPLUS_ATTRIBUTES 14 /* Mac OS extra attributes */
>> #define STREAM_UNIX_ATTRIBUTES_ACCESS_ACL 15 /* Standard ACL attributes on 
>> UNIX */
>> #define STREAM_UNIX_ATTRIBUTES_DEFAULT_ACL 16 /* Default ACL attributes on 
>> UNIX */
>>
>>
>>
>> So I think that only the md5sums on the volume are compared with the md5sums 
>> in
>> the catalog. If the file data on the volume was damaged somehow this could 
>> not
>> be detected.
>>
>
> The reason I think it is reading the volume is the comparison to the
> Catalog level which has to read the filesystem data to compare that to
> the md5sum in the catalog.
>
> http://bacula.org/5.0.x-manuals/en/main/main/Using_Bacula_Improve_Comput.html
>

I guess I can test this by creating an uncompressed disk volume for a
fileset containing a single text file then corrupting the data part of
the bacula volume and see what it does..

John

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