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  1. #1
    Join Date
    Jun 2012
    Posts
    3

    Talking Unanswered: Running two instances of Informix?

    Hi there everyone. A newbie to the forums.

    I am NOT a techie and get overwhelmed by acronyms (join Get Rid Of Acronyms Now!.........we call ourselves GROAN).

    We are running our Pharmacy system build on Informix 11.5 on an IBM p5 database server (type 9131-52A). We are negotiating with another hospital to host their same system on our database server (new install) but they would run off their own instance of Informix.

    How can I find out if this server can effectively run two instances in a production environment without any performance issues?


    Alternatively, does anyone have any experience in running two separate production databases off of the same instance of Informix? Any recommendations surrounding the advisability of doing so vis a vis performance/security/risk etc would be appreciated.

    Apologies if this is too basic for this forum but any assistance would be greatly appreciated. During our last upgrade, when we ran into server issues, the IBM support person wasn't terribly familiar with our hardware.
    Last edited by FordPrefect; 06-13-12 at 11:45. Reason: Other data required

  2. #2
    Join Date
    Nov 2010
    Posts
    16
    Quote Originally Posted by FordPrefect View Post
    Hi there everyone. A newbie to the forums.

    How can I find out if this server can effectively run two instances in a production environment without any performance issues?


    Alternatively, does anyone have any experience in running two separate production databases off of the same instance of Informix? Any recommendations surrounding the advisability of doing so vis a vis performance/security/risk etc would be appreciated.

    Apologies if this is too basic for this forum but any assistance would be greatly appreciated. During our last upgrade, when we ran into server issues, the IBM support person wasn't terribly familiar with our hardware.
    Well... the question is ok, but I'd say it's impossible to answer it... Let me explain why, and you may take it from there...

    Technically you can run up to 255 instances of Informix on a server. The reasons why running two can be impracticable are lack of resources... Like if you don't have enough memory or enouch CPU power, or disk storage (there is some overhead off having two instances instead of two databases).
    The reason why I can't answer your question is because "it depends". How much memory and CPU do you have free on the current system? And how much would you need?

    As for running two databases into one instance, plenty of customers do that. But there will be less isolation between the environments. Meaning a bad query will possibly cause more performance degradation that if you have separate instances (as long as you define the correct resources for each one). For example, if your system has 6 cores, you could configure one instance with 4 CPU VPs and the other with 2. With just one instance you'd set it to 6 and a bad query or bad program, could lead to the consumption of all these 6...
    Of course having two instances means more maintenance effort.
    In terms of security it wouldn't make much difference. By default Informix uses OS authentication, so a user in the system would be able to authenticate to both databases. Note however that authentication != Connection permission. So you'd have to be careful with the connection permissions (in both cases)

    Hope this helps, if not feel free to ask. Regards.

  3. #3
    Join Date
    Jun 2012
    Posts
    3

    Thumbs up This does help

    Thanks for the insight, domusonline. This does help in that it provides me with some technical points to raise in our call today. Much appreciated.

  4. #4
    Join Date
    Sep 2011
    Location
    Pont l'Abbé, Brittany, France
    Posts
    381
    Provided Answers: 1
    Hi,

    domusonline explained it all.
    Plenty of users do have multi-instances in dev, staging or test environments.
    Much less customers have multi-instances in production environments, due to the reasons that domusonline explained above.

    In this last case, you must tightly control resource allocation to each instance, in order not to have resource conflicts between each other.

    This was just to add something after domusonline :-)

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