Re: ASM and O/S Security

On Tue, 05 Apr 2005 15:18:39 +0200, Volker Hetzer interested us by writing:

>
> "HansF" <News.Hans_at_telus.net> schrieb im Newsbeitrag news:pan.2005.04.05.13.55.03.133148_at_telus.net...

> I'm still reading up on the whole thing. We are evaluating 10g and I want
> to get a db running that uses it on four disks. So far I have progressed to "I
> need to get the asm package first and have to make the disks available to that."
> When I talked about files furthe up in the thread I wasn't that far yet and thought
> that it all gets managed from the db instance and not from a separate one.

Ah - got it. (And apologies for my frustration)

The thing that tends to be confusing is that ASM is actually a separate server (as in software) and has it's own instance. In many ways it feels like a database instance that you don't take past the mount state, and some of the commands are even identical to those we use in managing a database instance.

The database instances then pass the data requests to the ASM server not unlike hosts passing requests to a SAN frame. And in a similar manner, one ASM instance can take requests from several database instances. The big conceptual difference, imo, is that a SAN uses disks and block stripes whereas ASM uses files (eg: tablespaces) and 'file chunk' stripes.

For almost 20 years I've said "Oracle is an operating system, albeit very specialized. A lot of similarities, including memory management. Equate tablespaces to disks, tables to files, and columns to fields and you have a comfortable grounding for learning Oracle." Now we add "ASM ~= SAN".

-- 
Hans Forbrich                           
Canada-wide Oracle training and consulting
mailto: Fuzzy.GreyBeard_at_gmail.com   
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