Oracle-L: RE: 20 Instances 1 Machine

From: Fink, Dan <Dan.Fink_at_mdx.com>
Date: Thu, 01 Aug 2002 15:13:37 -0800
Message-ID: <F001.004A9765.20020801151337@fatcity.com>

Ethan,

The points you make are valid. There will be some resource wastage due to the overhead of each instance and database, but the potential downside may make it worthwhile. Suppose customerA's application has a bug generates a ton of redo, overflowing the archive_dump_dest. This means that customerB's (and all others) data is unavailable and applications will begin to malfunction. Imagine telling irate CustomerB that they are down because of CustomerA! This also simplifies backup and recovery requirements that differ between customers.

There will be some performance penalties, but a sufficiently powerful machine should be able to mask them.

-----Original Message-----
Sent: Thursday, August 01, 2002 4:44 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
INET: Ethan.Post_at_ps.net

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Author: Post, Ethan
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