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@xxxxxxxxxxxxxxxxxxxx>
To: <richard.foote@xxxxxxxxxxx>; "Mladen Gogala" <gogala@xxxxxxxxxxxxx>
Cc: <DGoulet@xxxxxxxx>; <JBECKSTROM@xxxxxxxxx>; <oracle-l@xxxxxxxxxxxxx>; 
<ORACLE-L@xxxxxxxxxxxxx>; <oracledba@xxxxxxxxxxx>; 
<oracle-rdbms@xxxxxxxxxxxxxxx>
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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