Re: Is my Oracle Server issuing more IO than it can handle

From: Harel Safra <harel.safra_at_gmail.com>
Date: Tue, 07 Dec 2010 21:32:55 +0200
Message-ID: <4CFE8BE7.9030407_at_gmail.com>

Hi Niall,
This example was in perfect physics land where cows are spherical (http://en.wikipedia.org/wiki/Spherical_cow) and there is no friction.

In the real world you comment holds very true and you need to compare the active part of the database to the cache size.

Harel Safra

On 07/12/2010 21:15, Niall Litchfield wrote:
>
> Hi Harel,
>
> I assume you intended to compare the working set of database changes
> to the cache size rather than the database size itself. The 2 things
> are not well related.
>
> On 7 Dec 2010 19:12, "Harel Safra" <harel.safra_at_gmail.com
> <mailto:harel.safra_at_gmail.com>> wrote:
>
> This calculation is only true if you work with disk drive directly
> attached to you servers, and even then when there is no cache in the
> raid controller.
> Once you start working with central storage systems things like cache
> size, i/o distribution and disk sharing start to come into play.
>
> For example, our EMC dMX4 storage has 96GB of cache. If your database
> is smaller than that (and nothing else uses the cache in this example)
> you could get very high throughput even with a single physical disk.
>
> Do you know which kind of storage you use? Is you system the only
> system attached to it?
>
> Harel Safra
>
>
>
> On 07/12/2010 20:05, Oracle Dba Wannabe wrote:
>
>>
>> >
>> > Do any of you have any thoughts w.r.t to question 1 - whether those
>> calculations can be represe...
>>
>> thanks
>> ------------------------------------------------------------------------
>> **
>>
>>
>> > 1. Is there someway from awr that I can determine that the Oracle
>> server is issuing more IO than ...
>>

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Received on Tue Dec 07 2010 - 13:32:55 CST