Hi,

On 3/25/2007 5:39 PM, Marc Cuypers wrote:
> Hi Arno,
> 
> Thanks for answering.
> 
> Arno Lehmann wrote:
>> Hi,
>>
>> On 3/24/2007 9:16 PM, Marc Cuypers wrote:
>>> Hi,
>>>
>>> I'm still using bacula 1.38.5.
>>>
>>> To prevent shoe shining (writing, rewinding, writing again) with a tape
>>> drive bacula uses spooling.
>> ...
>>> The spooling to the file and the writing to tape is not concurrent.  Is
>>> there a reason for this?
>> Yes, but what it boils down to is that noone implemented a buffering 
>> scheme like using a circular buffer and filling and emptying it 
>> simultaneously. Note that many hard disk systems have already 
>> difficulties delivering data fast enough to allow streaming on todays 
>> tape drives. That would get worse if, due to concurrent writes and reads 
>> to one disk, access times increased.
>>
>>>  Has this changed in later versions?
>> No, not as far as I know.
>>
>>>  Are there
>>> any changes to be expected in this?
>> I doubt it.
>>
>>> I'm asking this because backups without spooling are faster than those
>>> with spooling.  Is this normal?
>> It can be normal, and in most cases is.
>>
>> Overall throughput will probably increase when you run multiple 
>> concurrent jobs.
> 
> When running concurrent jobs, each job will have its own spool file in
> the spooling directory?  And normally when a spool file fills for one
> job, writing to tape can begin, while the other jobs keep spooling?

Alan answered this already, so I just add my comment because you 
addressed me :-)

Yes and yes.

Arno

> --
> Best regards,
> 
> marc
> 
> Questionable day.
> 
> Ask somebody something.
> 
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-- 
IT-Service Lehmann                    [EMAIL PROTECTED]
Arno Lehmann                  http://www.its-lehmann.de

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