Re: Online creation/extension of Tablespaces possible??

From: Howard J. Rogers <hjr_at_dizwell.com>
Date: Mon, 13 Sep 2004 07:53:04 +1000
Message-ID: <4144c544$0$968$afc38c87@news.optusnet.com.au>

Daniel Morgan wrote:

> Howard J. Rogers wrote:
> 

>> Daniel Morgan wrote:
>>
>> [snip]
>>
>>

>>>I mean't raw ... sorry about any poor choice of verbiage.
>>>
>>>And yes I've seen Oracle's slide show and it is not what I teach, it is
>>>not what Oracle system specialists on this continent advise, and is in
>>>my opinion preposterous.

>>
>>
>> If you're going to create a RAC database, you need two controlfiles,
>> minimum. SYSTEM, two UNDO, TEMP and DATA, minimum. You need a *minimum*
>> of 4 redo logs, assuming just a two-node RAC, times two because you
>> multiplex them. You need an spfile. And you (probably) need a voting
>> partition. That's 17 things to store, for the barest, simplest database
>> with a minimum of multiplexing/safety features in just a two-node RAC.
>>
>> If you aren't going to create 17 separate raw partitions to house that
>> lot, I can't quite see how you're going to do it at all -short of
>> implementing a cluster file system, obviously.
>>
>> So it seems to me that a veritable plethora of raw partitions is an
>> absolute *requirement* for a RAC on raw, not a preposterous configuration
>> at all.

> 
> 17 is manageable. Breaking up one 36GB drive into 2GB partitions gives
> 18. And if you calculate this out over a 5TB database, not at all
> unusual these days ... do the math.
> 
>>>That said ... I don't see anything anywhere in my shop that has a 2GB
>>>limit other than Windows.

>>
>> Bzzzt!! Well, that's a good 30% plus of the Oracle installed base, then,
>> isn't it? (At least).

> 
> I can't argue this point as I don't know. But what I do know, from
> personal experience, is that I am aware of only a handful of companies
> in the area doing production Oracle on Windows.
> 
>   Good convert to the Other Side though I may be, you

>> can't just dismiss Windows like that. If it's true for Windows, it's true
>> for a lot of people.

> 
> Don't tempt me.  ;-)
> 
>>>I agree with sizing for backup/restore
>>>purposes.

>>
>>
>> Then we agree, which is the main thing.

> 
> Yes ... but 2GB?
> 
>>>But who has anything in their data center that considers 2GB
>>>a size limit?

>>
>> I'm not sure what that question means. I didn't mean to suggest that 2GB
>> is an actual size limit. Merely that I would like to think of it as a
>> *practical* limit in many circumstances. Of course, my opinion starts to
>> change when your database starts nosing into the 100GB+ territory. But
>> until then, 2GB is a sensible suggestion, I think.
>>
>> Regards
>> HJR

> 
> And I would like to think of 2GB as too small to be of practical
> interest: Maybe that's just an American thing.  ;-)
> 

Well, let's not prolong the debate -but I really don't understand the comment that '2GB is too small to be of practical interest'. We are talking file size limits here (limits in practice, that is, not hard-and-fast theoretical ones), but those mean nothing very much as far as the database as a whole is concerned. If I limited my filesize to 100MB, I would still be able to store 6.4TB of data in my database (because I am allowed 64,000ish data files in a database). Just because one makes a call on a realistic file size limit (which 100MB isn't, by the way!) does not mean you've compromised the ability of your *database* to "be of practical interest".

Would I invade a small, neutral country to insist on 2GB? Of course not (though Switzerland is a tempting target). If you want 4GB, I won't bite your head off. If you want 16GB, I might start sharpening the canines, however. Them's a lot of eggs to be putting in one basket. But ultimately, it's your omelette (oh dear) if it all goes wrong, so you make the call.

You tell me you're working for NASA and need to store 160 Exabytes of Voyager 2 data, and I think we can rapidly agree that even 16GB file size limits might be impractical. But on the grounds that I don't work for NASA (shame!), and neither do most people, I'll stick with my present advice.

Regards
HJR Received on Sun Sep 12 2004 - 16:53:04 CDT