Re: I/O wait question/scenario

On 24 Feb 2004 04:10:07 -0800, bordenm_at_methodisthealth.org (bordenm_at_methodisthealth.org) wrote:

>After the vendor has researched this a little, they have said the
>the I/O wait will go down once we add more users to the application.
>They are saying that the I/O wait is high because the processesors are
>so fast that it processes the transactions faster than what it can
>handle

This is by far the worst vendor bullshit I have ever seen here. The clock time is divided between user, kernel and I/O activities. If 60 percent of the time is spent waiting for disk, then 60 percent of the time is spent waiting for disk. A process will post an I/O request and simply go dormant until the I/O request has been satisfied. If the system wouldn't have to wait for disk, it would automatically devote it's time to other activities.
The vendor has absolutely *ZERO* clue as to how operating systems work.
Likely you have an unscalable application, and your problems will aggravate by adding more users.

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Sybrand Bakker, Senior Oracle DBA