Re: Multiple Instances Vs Multiple Servers

Mohamed El-Mallah <mie_at_mainruis.sannet.gov> wrote:

>Hi,
>We r comparing between two solutions :
>1- One big server running on it 3 Oracle instances with enough memory
>and diskspace.
>2- Three seperate servers on each one its own Oracle Instance.
>Could u help me in giving your opinions (pros and cons), especially if
>your site have one of these implementations, I will appreciate it.
>And one more question, could the Oracle Parallel server setup for one
>instance only on the multiple instances server.
>Thanks
>--
>Mohamed El-Mallah
>San Diego Data Processing Corp.

One large server with several instances may get you more raw processing power, but makes it harder to isolate the processing for the various applications. This includes tuning, installation, user load etc.

Several servers each with their own instance make for more maintenance of code but more scalability and easier maintenance per instance. For "instance" using SQL*Net, you can have users log onto one machine, yet point to an oracle instance on a different machine. So you can have user servers and database servers. This type of isolation isnot possible with a single server. Also, how do you want to do development, will you have dev, test, and prod instances?

These solutions also depend on the nature of the applications and the load. The single most frequent bottleneck is disk I/O, especially if there is only one server. Unless you have some really mongo disks with tremendous throughput, parallel server sharing a disk subsystem can cause bottlenecks, especially for queries to large tables.

You need to look at the mix of users, applications, time load, maintenance needs, and especially I/O from input and reporting to make a logical decision about this.

I hope this helps.

Wayne Balmer. Received on Fri Apr 11 1997 - 00:00:00 CDT