Howard J. Rogers wrote:
> Glen A Stromquist wrote:
>
>
>>Hi Howard - glad I could help!
>
>
> I'm sure you just did all of this so that I could learn, didn't you ;-)
>
>
>>Fixing it was no problem, by the end of the day yesterday I'd figured
>>out that compatible=9.2 was needed because of my system tablespace and
>>it was starting ok, so this morning just re-created an spfile from it
>>and all's ok, although I'm still reading to find out why I want to do
>>this over the old init file.
>
>
> See below.
>
>
>>I was using Kedit when I edited the original spfile, which must have
>>changed it to a text file when saved. At least now I know that a "*." in
>>front of a parameter does not affect the startup.
>
>
>
> True. And it will work just fine if, in an init.ora, you leave the * out as
> well. "*" just means 'all instances'. So does a lack of a "*". And that
> betrays the real reason why the spfile was invented: RAC. Because in a RAC
> you might want one instance to have an 80M shared pool, and the other to
> have 120M. So how do you distinguish between the two settings? You have:
>
> INST1.shared_pool_size=80M and
> INST2.shared_pool_size=120M
>
> The the right settings apply to the right instance. By the way, the command
> to set that up in an spfile would be:
>
> alter system set shared_pool_size=80M scope=spfile sid='INST1'; and
> alter system set shared_pool_size=120M scope=spfile sid='INST2';
>
> By default, the sid clause will be set to "*", so that by default any alter
> system that affects the spfile will apply to all instances in the RAC.
>
> By the way, the instance.parameter notation works perfectly well with a
> boring old init.ora, too. But the init.ora, being a mere text file, can't
> be dropped onto a raw partition... and unless you have gone to the expense
> of putting a cluster file system onto your shared disk (or taken the
> slightly brave step of using the freebie CFSes that Oracle have produced
> for Linux and Windows) then that must mean you can't have one init.ora that
> can be used to control the entire set of instances comprising your RAC.
> Hence the need for a binary version of the init.ora, which can indeed be
> dropped onto a raw partition.
>
> The other reason for Oracle switching to an spfile is that precisely because
> it's binary, the only thing that can edit it is your server process. And
> that's good, because it means the file is immune from the stupidity of
> users who think that including comments, explanations and change history
> within the init.ora is a good idea... it actually just results in an
> enormous mess which no computer system could hope to manage properly. So a
> binary version means that managing the file and, the important bit, making
> changes to it *automatically* becomes feasible. And in 9iR2 there's at
> least one bit of functionality that does precisely that: Data Guard. When
> you suddenly decide that you want one of your standby databases to be
> updated at a lag of 30 minutes instead of the current 15, that actually
> means 'change my LOG_ARCHIVE_DEST_3 parameter to include a DELAY clause'...
> but by talking to DMON (the Data Guard Broker) to request the change, you
> actually get DMON to modify the spfile for you, so you don't have to worry
> about *how* to implement the change, merely request *what* you want to
> change. So if you want Data Guard in 9iR2, you absolutely have to have an
> spfile.
>
> And that's a long-winded way of saying, the spfile will become more and more
> important to Oracle as a way of hiding from the user *how* to do things,
> and thus allow him or her to concentrate more of what it is they want done.
> If you want a self-tuning database, too, you're going to have to have this
> 'I will automate the configuration changes needed to secure a particular
> outcome' facility.
>
> Regards
> HJR
Got it, I was going to blow away the spfile and stick with init files,
but since this is a sandbox anyway I may as well keep it and get used to
it...
BTW, if you are using Linux a lot now you may want to try "gqlplus",
kind of a shell to run sqlplus in and allows use of the arrow keys to
scroll thru your sql commands like a dos window, very slick but I have
to figure out why it fills the sql buffer when I get time.
Received on Fri Oct 10 2003 - 10:56:39 CDT
