Re: [Bacula-devel] Alternative DB structures-Porposal

[John H. <Jo...@mi...>]

Ok Problem solved.

--John


David Boyes wrote:
>>> Reading a 20 TB file twice is nontrivial. I have LOTS of files that
>>> large, and a few that will grow into exabyte-scale in the not too
>>> distant future.
>>>       
>> I think we should just exclude those from consideration. What exactly,
>> can we back up a exabyte file to? A billion CD's!
>>     
>
> On the other hand, these are EXACTLY the files that need the database
> support most. Why would you want to exclude a real case that supports
> your argument? 
>
> (BTW, today, you store petabyte and exabyte-class datasets on 1 inch
> optical tape. About 350 TB/volume for the current generation, due to go
> up to about 600 TB in the next year or two with more efficient lasers
> and some of the material science research going on at 3M in the US, Univ
> Monash in Australia, and Siemens in Germany.)
>  
>   
>> If you must use bacula, for your (very much smaller 20Tb files) then
>>     
> do
>   
>> nothing
>> On those systems, you don't have a filesize for the reasons given. But
>> you  already don't a have a filesize,
>> so adding a size field to the catalogue changes nothing. Set it to
>>     
> zero
>   
>> or the number of blocks or something.
>>     
>
> Which is exactly what I suggested. In the general case, a file size is: 
>
> Number of units * unit size. 
>
> If unit size = 1, you trivially get the current semantics, and you lose
> a few bytes in the database storing the extra binary 1 for the unit size
> repeatedly. If unit size > 1, you lose a few bytes in the database and
> save boatloads of client backup time waiting for the FD system to get
> the info for the attribute packet. 
>
> Everybody wins. 
>
> -- db
>
>
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