Re: oracle grid

gigg wrote:

> anyone can tell me in few words how does "oracle grid" work? which is the
> mininum number of pcs necessary and what about their system requirements?
> thanks of all...

There is really no such thing as an 'Oracle Grid'. The "g" in 10g simply refers to an entire family of technologies which help virtualise processing power, so that you don't know where it's coming from -which is the entire ethos of grid computing ("processing power should be like water from a tap, or electricity from the socket: you get it when you need it, and you neither know nor care from whence it comes". I think I just made that up, but it sounds like it ought to be a quote from somewhere).

So, RAC does not go away in 10g. It isn't superceded. RAC is a core grid technology, because it means that the rows of data you see scrolling up your screen could be coming from one of several instances. With RAC's inter-node parallelism, your query could be being executed on any or all of several nodes simultaneously. The CPUs in those nodes have been virtualised into a single, giant processing resource.

ASM is similarly a core grid technology because it is a way of 'hiding' where your data is physically stored. With ASM, all you see is a huge, global storage pool. You don't know, and do not particularly want to know, where the block of the EMP table is physically housed. It's physical location has been virtualised almost out of existence.

Technologies such as ADDM (Automatic Database Diagnostic Monitor) are grid technologies because it shields you from having to worry about re-configuring a lot of initialisation parameters simply because you add some new hardware (an extra CPU, for example). Oracle will re-configure itself to take account of such changes, so that again there is a virtual cloak between you and the underlying hardware and associated software configuration.

I could go on, but we'll be here till Christmas. Point is, RAC can be used all on its own. I can create a single-instance database that stores its datafiles in an ASM array. I can use ADDM for a single instance database of the humblest sort... all (or most, anyway) of these technologies have an independent existence, and can be adopted or not as you see the need arise. It is when you put them all together that you have a self-managing, fully-virtualised, database processing resource ...and then you have a 'grid'.

So to answer your specific questions by way of wrap-up: there is no minimum number of PCs. There really is no one thing needed to make 'Oracle grid work'. Most of the grid technologies have a perfectly legitimate use for a single instance running on a single CPU (RAC being the obvious exception). Do the various technologies work well? I would have to say Yes, on the whole. I don't particularly think RAC is a sensible idea for everyone, but it is certainly fiendishly clever, and has had a couple of versions to bed-in. ASM is a very nice technology that I would be thinking of using for any database, not just big, RAC'd ones, but it's still a bit too new for me to trust completely just yet.

Regards
HJR Received on Wed Sep 15 2004 - 15:18:39 CDT