Re: type of striping

Howard J. Rogers wrote:
>
> It might have done. But I get a lot of spam 'Mail could not be
> delivered'. I wouldn't notice a real one of those amongst the others.
>

Pity for the mail(s) I have lost.

>
> I wasn't suggesting you had a position. I was merely pointing out that I
> don't particularly have one either.
>
> Autoallocate very rarely fragments. Richard Foote's posted some good
> examples of that here not too long ago (search at Google). *Can* it
> fragment? Yes. But it's difficult to make it do so. But even if it does
> fragment, is that a performance problem? No... it's a waste of space
> issue, and you can still do coalescing of free space if it's really
> serious (which it won't be, probably).
>
> The pros are, therefore, that it's entirely automatic. It frees you up
> from worrying about extent sizes in the future. It fits into the 10g ASM
> framework of total automation. It is hard to fragment. It spares you the
> embarrassment of having made the wrong judgement about which UNIFORM
> SIZE to choose. It fits with ASSM nicely.
>
> The cons are that it can, with difficulty, fragment a bit.
>
> That's about it as far as I can tell. (Don't forget to read Holger's
> post where he points out something I'd totally forgotten: that if your
> table is big enough (>1M), autoallocate even starts round robin-ing the
> extents again).
>
> There's really very little to say against them. I think most DBAs are
> more likely to make damaging mistakes in extent size choice with uniform
> size LMTs than are ever going to suffer from choosing autoallocate.
>
> [Going back to your original question, by the way: I have long advocated
> uniform sized LMTs should have 64K, 1MB, 8MB, 64MB and 256MB extents.
> Those are, in fact, precisely the extent sizes you'd get in
> autoallocated tablespace. In other words, even my old posts suggested
> doing things manually in a way that the automatic way would have done in
> any case. It's just taken me a while to realise that such a position is
> a bit daft: if I'm going to recommend doing what autoallocate does
> anyway, why not simply recommend doing autoallocate and have done with
> it?!]
>

Thank you for the explanation. It helps.

Still I'm a little bit concerned about ASSM... but probably it is only prejudice.

Regards

-- 
Fabrizio Magni

fabrizio.magni_at_mycontinent.com

replace mycontinent with europe