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  1. #1
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    Exclamation What happens if Online and Offline are down?

    Hello All, I have a problem and would like your help. I have created a scenario below. An elaborated response would be appreciated. Thank you for taking the time to answer.

    A nation-wide company such as a bank has a Central database located at IBM’s Blade Center where data is stored to communicate with other branches/stores. These branches located anywhere in Canada have a Web Service application that allows Customer Service Representatives (CSR) to create, read, update and delete customer banking transactions and applicable data. In the event that Internet connectivity is down the Bank has an offline plan. The offline plan consists of each store having a local database with a Master computer and Slave computers.

    The Slave computers are other computers in the store that depend on the Master computer which holds the Local database. The Local database allows local transactions if connection to the Central database is lost. All local transactions data will be stored in the local database and transferred to the Central database automatically when Internet connectivity is restored. Each night the Central database synchronizes its data with all local databases. The local databases should therefore never be less than one day old which makes synchronizing a smooth process. If by chance more than one store modifies the same customer’s transactions they would receive a warning dialog box telling the CSR to contact head office. Head office will then take care of this.

    Being that the Central database is down my question is, what technique can be done if a store’s Master computer which holds the local database becomes unavailable? At this point no operations can take place through the Slave computers. Therefore no transactions can occur. Common issues seen while a store is offline, and the master computer is not available is application errors and / or timeouts while saving or retrieving data on the slaves, or the application stating the user’s credentials are incorrect upon logging in. What can be done?

  2. #2
    . shoooo... silver trophy logic_earth's Avatar
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    Well you can first have multiple internet connections, multiple local and remote servers, several datacenters, etc. Build a redundant system with as much backup hardware as possible...of course that is possible is money is no object. However, if everything is down then the only thing that can be done is to get your butt in gear and fix it.
    Logic without the fatal effects.
    All code snippets are licensed under WTFPL.


  3. #3
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    What are your thoughts on individual air cards and VPN client installed for a secondary backup?

  4. #4
    SitePoint Author silver trophybronze trophy
    wwb_99's Avatar
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    That helps the "our main net connection is down" angle, but doesn't cover alot of other scenarios, such as "our blade center is on fire". I'd also argue that, for a bank, day old data is a day too old. Unless you want me to be able to withdraw $10k from my account in vancouver, hop on a plane and then withdraw that same $10k from the same account in Toronto.


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