Re: separate tablespaces for tables and indexes

Hi Mladen

I'll try one last time then give up, remembering it was only a simplified example.

My point is that previously *one* disk associated with a tablespace had 1000 I/Os, the other disk associated with the indexes had 100 I/Os.

So yes, a combined *tablespace* now has 1100 I/Os but I would now have *two* disks thereby evening the load across the *two* disks (say 550 I/Os on *each* disk),

Now read my initial comment that in many environments that have separate disks to split tables/indexes in the *hope of reducing contention*, potentially have *hot* 1000 I/O disks and cold 100 I/O disks rather than evenly loaded disks.

And no, not all sites have SANS and the such and yes some sites still partition their SANS in the above manner (Insane SAN).

That's all ...

Richard
----- Original Message -----
From: "Gogala, Mladen" <MGogala_at_allegientsystems.com> To: <richard.foote_at_bigpond.com>; "Mladen Gogala" <gogala_at_sbcglobal.net> Cc: <DGoulet_at_vicr.com>; <JBECKSTROM_at_gcrta.org>; <oracle-l_at_freelists.org>;
<ORACLE-L_at_IC.SUNYSB.EDU>; <oracledba_at_LazyDBA.com>;
<oracle-rdbms_at_yahoogroups.com>

Sent: Wednesday, December 15, 2004 12:57 AM Subject: RE: separate tablespaces for tables and indexes

Richard, I am still not convinced, and for the following reason: The alternatives were: splitting indexes and tables in their separate tablespaces vs. leaving them in one tablespace. If you leave them in one tablespace, then 1100 LIO/sec is what you get, because both of your disks will be a part of the same tablespace. Tablespace blocks are allocated sequentially and, if you put both "disks", in the same file, you will end up exactly with what you say you don't propose. In order to make separation policy viable and easy to document you have to adopt one of the two principles mentioned before. Second policy (size based) does not put indexes and tables in the same tablespace, because indexes are usually smaller. The first policy would render exactly what you described as a big no-no: everything in a single place, with 1100/sec.

--
Mladen Gogala
Ext. 121



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