ATOL: Cluster and Services
Marek Grác
xgrac@f i.muni.cz
Red Hat Czech s.r.o. / Faculty of Informatics, Masaryk University
Advanced Topics of Linux Administration
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►  High availability failover of service groups
►  Designed for 'cold' failover (application stop/start)
►  Works with off-the-shelf application
►  No difference between resource (e.g. IP address) and application (e.g. Apache)
►  SystemV-style init script
►  Failover domains
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►  Service group contains of 1+ resource agents (IP + apache + mysql + filesystem)
►  Start/Stop sequence of resources (IP before apache) does not depend on order in configuration
►  Resource agent has access to both siblings and child nodes in XML (a bit of inconsistency)
►  clustat - cluster status
►  clusvcadm - cluster services administration (cli tool) or lucii
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►  Recover policy is defined when service is created
►  Policies:
►•   Restart - tries to restart failed parts of group before relocate
(default) ►•   Relocate - move on another node ►•   Disable - disable entire service
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►  Create a simple service containing of IP address and move it on other node (then add failover domain)
►  Create a service group for NFS export (parent-child data passing) - filesystem, nfs export, nfs client
►  Create a service group for apache (sibling data passing) -apache, i p address
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►   Create a service group for LAMP application (use NFS export from physical machine)
►  Add support for connecting through ssh to such service group
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► Themes:
►•   Explain how to create a resource agent for application and describe problems
Format:
►•  Short presentation (15-20 minutes; 5-7 slides) ►•   Paper containing comparision (1.000 words)
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