>I want to backup my database so that some data is omitted from the
> backup. I'm trying to do it like this:
>
> 1. issue "alter database begin backup"
> 2. copy database file to temp file
> 3. issue "alter database end backup" on original database
> 4. delete unwanted data in temp database
> 5. backup temp database
>
> I get error on step 5:
>
>> I/O error for file
>> "C:\_POSSU\POSSU3\TEMP\$20080306174036359$.TMP.delta"
>> Error while trying to open file
>> The system cannot find the file specified.
>> internal gds software consistency check
>> (Error: can't actualize backup state)
>
> "C:\_POSSU\POSSU3\TEMP\$20080306174036359$.TMP" (NB withoud ".delta")
> is my temp database file
>
> I read from FB 2.0.3 relnotes about nbackup responsibilities :
>
>> 2. to fix up the database after filesystem copy
>> (physically change nbak_state_diff to
>> nbak_state_normal in the database header)
>
>
> Can it be my problem that i didn't make this change?

Exactly

> How to do this by hand?
>
> (i'd like to avoid shipping nbackup.exe)

Read or use the nbackup sources, it is very simple utility.

Regards,
Vlad