- Red Hat Enterprise Linux (RHEL) 5 or 6 with the High Availability Add-On
- Multiple resources that have dependencies between them in some way
- I have three services configured that are related: One with an
ip, one with an
fs, and one with
mysql. When they start the
mysqlservice fails and we're not sure why.
- I'm trying to create multiple services that contain resources which depend on each other, and they're not starting in the correct order. How can I configure them to start properly?
- How do I share resources across different services with
Place related or dependent resources in the same
rgmanager service in
Resources that must be started together on the same node need to be in the same service. When resources are in separate services, there can be no guarantee that they will always run on the same node, even if they are in the same failoverdomain. rgmanager will start these services indepedently, which may result in them being operated on in an unexpected order, and if a problem is encountered with any one service it may relocate to another node whereas the rest of the resources/services stay in their preferred locations. There are dependency options that can tie one service to another as far as starting them in the correct order, but these bring no guarantee that those services will be colocated on the same node.
As such, the only way to guarantee proper colocation and start ordering amongst resources that depend on each other is to place them in the same service in the desired order.
pacemaker offers much more flexibility in this area, and should be considered for any cluster deployments which need finer-grained control over its resources than
rgmanager can offer.
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