On 2/24/2010 9:25 AM, Silver Salonen wrote:
> On Wednesday 24 February 2010 15:58:57 John Drescher wrote:
>    
>>> OK. I have never used tapes with Bacula. But I'd expect a file-type device
>>>        
> to
>    
>>> be able to load more than 1 volume at a time. It's quite trivial, isn't
>>>        
> it?
>    
>>>        
>> This was a design decision that all devices are treated the same way.
>>      
> It's like assuming that the "ultimate" backup-devices are tapes. And as I
> don't think that way, it's so annoying these design decisions rely on
> somebody's (emotional/historical) opinion.
>    

The ultimate is a stream of bytes that makes up a Bacula volume. In this 
way, a bacula volume is not media dependent, in that it doesn't matter 
whether that volume is on tape, disk file, DVD, FIFO, etc. The design 
decision separates backup function from I/O details.

> What's the use of treating all the devices the same way anyway? Ease of
> programming? Even though it makes this part of the whole project so rigid?
>    

Bacula is following the Unix paradigm of "everything is a file", which 
is to separate functionality from i/o details. Not everyone agrees, 
perhaps, but it is a time tested method that has proven to work and is 
trusted. Trust is of primary importance for any backup system.

>    
>>> Anyway, the "1 volume at a time"-limit has always been "one job at a time"
>>>        
> in
>    
>>> my head, because I put every job into separate volume/file (which makes
>>>        
> the
>    
>>> most sense in disk-based backups, to my mind). And when 5.0 was released
>>>        
> with
>    
>>> possibility to change limits of concurrent jobs for a device, I thought:
>>> "That's what I've been waiting for!". Thus the confusion. Sorry :)
>>>
>>>        
>> Add more disk storage devices. There is no limit to the number of
>> these.
>>      
> Yes, well, that's the problem. When I really need concurrent jobs, I've done
> that, but it seems so weird, redundant.
>
> --
> Silver
>
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