On Fri, Jun 20, 2003 at 08:49:20AM -0400, Jason Edgecombe wrote:
> 
> Can the estimate phase of amanda be bypassed or disabled?

No builtin way.
Too much of the remainder of amanda's design expects the results.

What some people have done is provide a wrapper for the dumper
program, tar or dump.  Since you mention tar, I'll use that as
an example.

When you build amanda, run configure, but don't let it discover
where gnutar it located, tell it using the --with-gnutar=....
option.  But the .... should be something of your choosing,
say "/usr/local/libexec/amgtar".  Now amgtar can be several
things, a copy of the real gnutar or a link to the real guntar
would result in a system exactly like you have now and would
be a good first shot.

However, now you can replace amgtar with a script or compiled
program that does one thing during the estimate phase and a
different thing during the dumping phase.  If properly written
amanda will have no idea she is not calling the real gnutar.

The arguments are quite structured and are recorded in the
various debug logs.  The way to tell if it is an estimate pass
or a dump pass is the output file.  Estimates use an output
file of /dev/null.  BTW this tells the real gnutar to not dump
anything, just scan the file system and give a report.  Surprisingly
this can be more cpu intensive, though shorter duration, than
a real data dump.

If the call to amgtar is a dump pass you can simply pass all the
scripts arguments to the real gnutar.  If it is an estimate pass
but not a file system that needs special attention you can also
call the real gnutar.  If the filesystem needs special treatment
you can call another script or code in something that gets your
results for you, like a "df -k <file system>" if it is a level 0
dump of an entire file system.  Extract the numbers you need,
put them in the format that gnutar would return, and pass them
back.  Done in seconds.

Replace df with any technique of your choosing.  Or if it is a
subsection of a file system or a level 1,2,3,..., adjust the
number for your guesstimate of the size.


-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
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