Jeffrey J. Kosowsky wrote:
>
>  > Collisions aren't quite the point - you have to manage that anyway.  The 
>  > hard part is knowing that the final target you link to is the one that 
>  > you wanted, not a something created simultaneously by a different 
>  > process doing the same computations, and knowing that the count of 
>  > existing links always matches the actual copies.  The kernel manages 
>  > this automatically when using links.  If you have to add an extra system 
>  > call to lock/unlock around some other operation you'll triple the overhead.
> 
> I'm not sure how you definitively get to the number "triple". Maybe
> more maybe less. 

Ummm, link(), vs. lock(),link(),unlock() equivalents, looks like 3x the 
operations to me - and at least the lock/unlock parts have to involve 
system calls even if you convert the link operation to something else.

> Les - I'm really not sure why you seem so intent on picking apart a
> database approach.

I'm not. I'm encouraging you to show that something more than black 
magic is involved.  Databases sort-of work for some things.  They aren't 
particularly better at storing files than a filesystem.  If they were, 
we wouldn't use filesystems for anything.  You've made a bunch of claims 
about how a database might be better, but so far have not provided any 
evidence to back it up.

> I can understand someone arguing that it would take
> too much effort to implement but I don't see the point of challenging
> the workability of a database approach, particularly when most high
> end enterprise backup systems do just exactly that (and for good
> reason!).

One of the 'good reasons' is that most of those systems were designed 
for an OS that didn't have a decent filesystem at the time...

-- 
   Les Mikesell
    lesmikesell AT gmail DOT com


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