Re: Poor mans RAID10...

From: Holger Baer <holger.baer_at_science-computing.de>
Date: Mon, 15 Mar 2004 19:07:15 +0100
Message-ID: <c34rck$lhb$1@news.BelWue.DE>

Volker Hetzer wrote:

> "Brian Peasland" <dba_at_remove_spam.peasland.com> schrieb im Newsbeitrag news:4055E487.80164F61_at_remove_spam.peasland.com...
> 

>>Volker Hetzer wrote:
>>
>>>Hi!
>>>I'm thinking of distributing one tablespace across several spindles simply by
>>>having one tablespace consisting of several datafiles.
>>>
>>>Does anybody know about how oracle (9i, Linux) actually allocates space
>>>across the different datafiles?
>>>Is one table always in one file or is the granularity the extent?
>>>
>>>Lots of Thanks!
>>>Volker
>>
>>An extent is allocated in a datafile. The next extent for the table
>>could be allocated in another datafile. But you can not be sure that
>>this will happen.

> 
> This is right. I whish there were a better solution but true RAID10 is
> out of the question.
> 
> Lots of Greetings!
> Volker

If you insist on evenly distributing and if you like administrative nightmares, then there's always the alter table ... allocate extent option:

http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96540/clauses2a.htm#78182

With that you can preallocate your extents, nicely distributed over your datafiles. Don't know how they'll actually get filled ;-(

HTH Holger Received on Mon Mar 15 2004 - 12:07:15 CST