Re: 10g ASM is junk ...

"Domenic" <domenicg_at_hotmail.com> wrote in message news:c7e08a19.0405241711.3c55f744_at_posting.google.com...
> I've been looking over ASM in 10g. Am I the only one who thinks ASM
> is a piece of junk? It looks like software-based RAID, and you need
> to take on the overhead of an ASM instance. How can this possibly be
> faster or better than striping/mirroring at the operating system
> level?
>
> I can't understand why Oracle would waste so much time and money on a
> feature that is better handled at the OS level (and easier too). So
> if the ASM instance fails -- BANG, the other instances can't see the
> disks anymore? I don't think anyone in their right mind would use
> this.
>
> Just my 2 cents ..
>
> Dom.

I am inclined to agree with you to some extent, but you've put the matter so strongly that you are not likely to encourage a great deal of debate from anyone else here.

The only thing I would say is that ASM is not just software RAID. RAID (1) merely stripes, not intelligently/evenly distribute -which is what ASM is trying to do. Plus, last time I checked you can't just plug in an extra disk to a RAID stripe set. You can (allegedly) with ASM, which 'grows' as new hardware is made available to it.

It's also true that ASM is trying to do a lot of things that RAID does not, such as protect your files from stupid user intervention (because there is no manual interface to ASM storage). And trying to answer the eternal cooked v. raw debate.

That said, I wouldn't trust my data to it just yet (first release etc etc etc). But if you sit there not 'understanding why Oracle would waste so much time' on it, it's probably because you haven't actually understood the totality of what they were attempting to do with it. If it was merely a RAID replacement, I think your comments would be sound. But it isn't.

As for being worried about your ASM instance failing and "BANG - the other instances can't see the disks any more"... one could just as easily have written that about a hardware RAID controller going BANG! But in any case, I don't think it's true. The job of the ASM instance is merely to hand each database instance an extent map as it starts up. Once the database instance is up and running, it is itself responsible for doing all the I/O, not the ASM instance. So the ASM instance can die, and your existing databases will still be viable.

That's only as I've read it, however, and I haven't actually gotten to test it. So anyone that has (Daniel, probably) can probably enlighten us to the contrary.

So I think there is definitely a debate to be had on ASM, and its usefulness. But I don't think opening the matter with a line saying, effectively, 'you can't be in your right mind if you use it' is calculated to make that happen particularly well!

Regards
HJR Received on Mon May 24 2004 - 21:52:52 CDT