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    Leganto EU00 - RCA - September 24, 2019


    This document serves as a Root Cause Analysis for the service interruption experienced by Ex Libris customers.
    The goal of this document is to share our findings regarding the event, specify the root cause analysis, outline actions to be taken to solve the downtime event, as well as preventive measures Ex Libris is taking to avoid similar cases in future.

    Event Timeline

    Service interruption was experienced by Ex Libris customers served by the Leganto EU00 instance at the Amsterdam Data Center during the following hours:

    September 24, 2019 from 09:15 AM until 11:30 AM Amsterdam time.

    During the event the service was partially available for the environment.

    Root Cause Analysis

    Ex Libris Engineers investigated this event to determine the root cause with the following results:

    Fixing a DNS High Availability configuration issue in the Secondary DNS server via the DNS management system resulted in a DNS failure, due to a bug in the management system.
    In order to restore application functionality, the fix was rolled back and cache refresh was executed on all the Data Center servers.

    Technical Action Items and Preventive Measures

    Ex Libris has taken the following action and preventive measures to avoid such an occurrence in future:


    • Ex Libris engineers rolled back the fix and executed cache refresh on all the Data Center servers, in order to restore application functionality.
    • Ex Libris engineers are working with the DNS Management system Vendor, to find the root cause of the malfunction that caused the DNS failure.
    • Enhancement to the DNS monitoring is being added.




    Customer Communication

    ExLibris is committed to providing customers with prompt and ongoing updates during Cloud events. Ongoing and prompt updates on service interruptions appear in the system status portal at this address:

    These updates are automatically sent as emails to registered customers.

    Publication History

    Date Publication History
    October 7, 2019 Initial Publication



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