This is not a bextract error per-se, rather when Bacula is reading the 
volume, the checksum it found in a block is not the same as the checksum 
it computed with the data that was read.  Normally this means that your 
disk drive is going bad.  In your case, you aare using a mounted volume, 
and in addition to the possibility of having a broken disk, there are 
possibly networking errors, and possibly errors with NFS. I dislink CIFS 
and NFS for Bacula volumes, because if you write something to those 
Volumes, then read it back, you do not always get the same data -- some 
of the data may be buffered and not actually written to disk.

Probably the best way to dig into this is to setup a job that does a 
VerifyData on the job that was backed up.  This will tell you if Bacula 
is able to read back a job that it wrote.  Note, this feature 
(VerifyData) only exists in Bacula version 7.4.0.

Another thing to do would be to run bls to list the blocks on the volume 
-- I am not sure it computes checksums though.

Best regards,
Kern

On 02/24/2016 06:37 PM, Andrea Venturoli wrote:
> Hello.
>
> I'm getting an error and having an hard time figuring the reason, so I'm
> looking for some insight.
>
> I have a job that backups a Windows client. It
> _ dumps some databases in "Client Run Before Job";
> _ backs the dump files normally to a NAS which is running bacula-sd;
> _ runs a "Run After Job" script that:
>     mounts that NAS via NFS;
>     runs bextract on the storage file used by the job;
>     uploads those file somewhere else.
>
> It has been working flawlessly for a long time, but in the last two days
> I'm getting messages like:
>
>> 23-Feb 22:52 dir JobId 5202: AfterJob: bextract: butil.c:289-0 Using device: 
>> "BackupXXXXXX" for reading.
>> 23-Feb 22:52 dir JobId 5202: AfterJob: 23-Feb 22:52 bextract JobId 0: Ready 
>> to read from volume "GestI1242" on file device "BackupXXXXXX" 
>> (/mnt/XXXXXXbackup).
>> 23-Feb 22:52 dir JobId 5202: AfterJob: bextract JobId 0: -rwxrwxrwx   1 root 
>>     wheel      300042752 2016-02-23 22:51:07  
>> /usr/local/local/XXXXXXDBs/2016022322521456264333/C:/Users/Public/Bacula/1.bak
>> 23-Feb 22:52 dir JobId 5202: AfterJob: bextract JobId 0: -rwxrwxrwx   1 root 
>>     wheel      187002368 2016-02-23 22:51:12  
>> /usr/local/local/XXXXXXDBs/2016022322521456264333/C:/Users/Public/Bacula/2.bak
>> 23-Feb 22:52 dir JobId 5202: AfterJob: 23-Feb 22:52 bextract JobId 0: Error: 
>> block_util.c:352 Volume data error at 0:53803237!
>> 23-Feb 22:52 dir JobId 5202: AfterJob: Block checksum mismatch in block=835 
>> len=64512: calc=6c456dfa blk=f9b4bb13
>> 23-Feb 22:52 dir JobId 5202: AfterJob: 23-Feb 22:52 bextract JobId 0: Error: 
>> file_attrs.c:568 File size of restored file 
>> /usr/local/local/XXXXXXDBs/2016022322521456264333/C:/Users/Public/Bacula/2.bak
>>  not correct. Original 187002368, restored 90963752.
>> 23-Feb 22:52 dir JobId 5202: AfterJob: 2 files restored.
>
> There should be 4 restored files, but the second gives an error and the
> procedure stops.
>
> I know NFS has problems with very large files (>2GB), but the storage
> file in this case is less than 100MB.
> What can cause that "Volume data error"?
>
>    bye & Thanks
>       av.
>
> P.S. The version is 7.0.5 on FreeBSD 9.3 and the NAS is a Zyxel NSA-310
> (I've been using several such objects with bacula without problems for a
> long time).
>
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