Re: switch from file system to raw device

From: Howard J. Rogers <hjr_at_dizwell.com>
Date: Thu, 16 Sep 2004 21:49:36 +1000
Message-ID: <41497dcd$0$1024$afc38c87@news.optusnet.com.au>

Hans Forbrich wrote:

> Igor wrote:
> 

>> Thanks for your comments.
>>
>>> If your environment is that susceptible to the disk performance, you
>>> might also get some benefit from the old (myth-age) style of separating
>>> tablespaces to separate disk drives & controllers, etc. However, other
>>> than for keeping someone busy, I would not recommend resurrecting those
>>> techniques!
>>
>> We did so when there was something to separate on, when we had disks,
>> which where seen/addressable individually. As we passed from single disk
>> handling (IBM SSA 7133) to Raid5 (IBM FAStT SAN), there of course is not
>> really much one can address individually. But in fact, we separated rbs
>> from tmp, data from indexes and so on.

> 
> From a performance perspective, according to the SAME (stripe and mirror
> everywhere) supporters there is little, or even negative, benefit to
> separating indexes from tables, etc.

I can't help it!

That there is no performance difference in separating or not separating indexes from tables has got nothing to do with whether you are using SAME or not.

Even if Oracle is implemented on JBOD (just a bunch of disks), with traditional file systems, and not a whiff of RAID in sight, there is still no intrinsic performance degradation from combining indexes and tables in one tablespace.

The lack of a performance hit arises from the way tables and indexes actually work, not the way they happen to be physically stored.

Of course, SAME adds yet another argument to the 'don't bother for performance reasons' school of thought's armoury. But it's not the sole or even main reason.

Regards
HJR Received on Thu Sep 16 2004 - 06:49:36 CDT