RE: 64 node Oracle RAC Cluster (The reality of...)

 >Bill Bridge is involved in writing it. Whether it will be fast
>is an open question, because even Bill can't change the laws
>of physics.

I've known Bill for many years through my decade long engineering work in the Sequent port of Oracle. So you must know then that ASM is a marketing name for OSM. "Oracle Storage Manager", became "Automatic Storage Management" magically with the flitter of the marketing pen :-) Bill also spec'ed the ODM library which interestingly only Veritas and PolyServe have signed up for, and implemented... Anyway, the important things about ASM I like. Things like the ability to migrate hot segments between datafiles. That is, however, a feature that could have just as easily been implemented in any datafile type...FS,raw or ASM. The things I don't like about ASM are the things that no datacenter should care about. For instance, ASM was hijacked by marketing as "the Veritas killer". It is no such thing, and no datacenter should care whether Oracle kills Veritas or not. How does Oracle "killing" Veritas help a datacenter deployment of Oracle in any way? ASM is software RAID. And it doesn't do it as good, nor as general purpose, as 3rd party solutions. To understand my point, you have to accept the fact that there is other software in the datacenter that has nothing to do with Oracle and common-ground platform choices are important.

>less complex than a full featured CFS. The functional
>requirements are a tiny subset of a CFS, and only precisely
>controlled "clients" will be able to request well defined
>services from ASM.

that is exaclty my point. so what do you do with the myriads other data that can't get stuffed into ASM?

BTW, the code path for a CFS direct IO measures in the sub-percentage difference from character special raw device access. I've done way too many instruction traces. If you want to account for lost processor cycles, look first to the code that executes hundreds of thousands of times per second, like Oracle spinlocks (latches). I'm not saying that Oracle spinlocks are inefficient, but slice the processor pie before talking about how big any one certain piece might be.

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