Re: [Bacula-devel] Code submissions

[Jake S. <ja...@ro...>]

Hi Kern.

I'll take a look at the developers guide and get back to you, thanks for 
the pointers.



>> The features that I'd like to work on are :
>>   - Automated configuration of storage devices in a library (using
>>     serialization)
>
> It would be nice to have automated configuration of storage devices, but
> unless you have some trick, it is generally quite system dependent, and we
> try as much as possible to avoid system dependent code.  In addition, storage
> configuration at all but the very largest sites is generally done once in
> about 10 minutes when initially installing Bacula.

Most modern libraries can return the list of drives they have along with 
their serial numbers.  You can then match the serial numbers up with the 
results of a SCSI device probe and auto-configure the whole lot (including 
auto-detection of the device type with help from the inquiry strings).

Even with a single host, a library with more than a couple of drives 
becomes hard to configure as you need to know which drive index maps to 
which local device before hand.  When you share devices amongst hosts this 
is gets very error prone.  Also your device numbers sometimes change which 
means you need to reconfigure manually -- if you have an automated method, 
this is less of a headache.  I'll dig into the library query details to 
see how easy all this is..


>
>>   - Support for native Linux changer device (more robust that MTX in my
>>     experience)
>
> If it requires Bacula to send SCSI commands to the control channel, then it is
> very unlikely we would accept the code.  It is much better to have such
> highly dependent system code in a separate program.  If you can write better
> code than MTX, it might be worthwhile creating a new program.  If Linux has
> some simple way of working an autochanger that can do everything that MTX can
> in the same simple ways that MTX works, that could be interesting.


My limited experience of MTX is that its very very unreliable.  For 
instance, my box here sometimes tells me that I have 2 drives and 45 
slots.  Other times it does the right thing and returns 6 drives, 45 slots 
and 12 mail slots.

Try 'modprobe ch'.  That'll give you a /dev/sch* device.  The utilities 
are available from http://linux.bytesex.org/misc/changer.html.  'mover' 
uses /dev/sch*;  I've seen this to be much more reliable using several 
types of changer.  Same with FreeBSD and its native changer device.  I 
think Solaris has one now too..




Jake