Oracle-L: RE: 20 Instances 1 Machine

From: DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Date: Fri, 02 Aug 2002 09:05:25 -0800
Message-ID: <F001.004AA137.20020802090525@fatcity.com>

Ethan - Now that you have clarified the reason why you want 20 instances, I'll change my advice and say that in your situation, 20 instances may be the better choice. Two other factors you need to consider:

An ASP is a lot like the old time-sharing systems. You must have an absolutely bulletproof billing system. This may be easier to accomplish if you have each customer in a separate O.S. username. You might be able to use the O.S. usage reports for billing with separate userids. And you must have good security to keep them from becoming root and giving themselves a discount.
Eventually you will need to upgrade Oracle versions. Not all customers will be able to upgrade at the same time due to other constraints on their part. Separate instances will allow you to have different customers on different Oracle versions.

Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Thursday, August 01, 2002 5:44 PM
To: Multiple recipients of list ORACLE-L

I am going to reply to this myself before I get flamed. I found a recent discussion on usenet regarding this topic.

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&threadm=3d1091af %240%2428006%24afc38c87%40news.optusnet.com.au&rnum=15&prev=/groups%3Fq%3Dto o%2Bmany%2Binstances%2Bgroup:comp.databases.oracle.server%26hl%3Den%26lr%3D% 26ie%3DUTF-8%26oe%3DUTF-8%26start%3D10%26sa%3DN

Basically everyone is against this idea. However no actual technical details are provided to explain why this could not be done in a production environment with the right sized machine. The scenario presented in which one would want 20 instances on a machine is in a class room setting. However, my scenario would be acting as an ASP. Each instance would support a different customer. My fear with splitting customers up into different schemas on the same instance is that I don't want to interupt other customers if recovery is required. This would have to be a tablespace point in time reco since we would only want to reco one customers data. Perhaps this isn't as big an issue if we go with RMAN?

Ethan Post
(972) 577-6552
Ethan.Post_at_ps.net
perotdba (AIM), epost1 (Yahoo)

-----Original Message-----
Sent: Thursday, August 01, 2002 4:58 PM
To: Multiple recipients of list ORACLE-L

I got a request to spec out a machine that could handle 20 separate Oracle instances on a single UNIX server. SGA should total about 500 MB per instance. We have some hosts here with 6-8 instances but never tried 20 before. Wondering what types of things I should be worried about, obviously having enough memory but are there any other limitations I can expect? Anyone had to do this?

Thanks,
Ethan
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Author: Post, Ethan
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Author: Post, Ethan
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