Monitoring Disk Resources
Rules for Using the EMS Disk Monitor with MC/ServiceGuard
Rules for Using the EMS Disk Monitor with MC/ServiceGuard
The disk monitor is designed especially for use with MC/ServiceGuard to provide package failover if host adapters, busses, controllers, or disks fail. Here are some examples:
•In a cluster where one copy of data is shared between all nodes in a cluster, you may want to fail over a package if the host adapter has failed on the node running the package. Because busses, controllers, and disks are shared, package fail over to another node because of bus, controller, or disk failure would not successfully run the package. To make sure you have proper failover in a shared data environment, you must create identical package dependencies on all nodes in the cluster. MC/ServiceGuard can then compare the resource “UP” values on all nodes and fail over to the node that has the correct resources available.
•In a cluster where each node has its own copy of data, you may want to fail over a package to another node for any number of reasons:
•host adapter, bus, controller, or disk failure
•unprotected data (the number of copies is reduced to one)
•performance has degraded because one of the PV links has failed
For example, in a cluster of web servers where each node has a copy of the data and users are distributed for load balancing, you can fail over a package to another node with the correct resources available. Again, the package resource dependencies should be configured the same on all nodes.
Disk availability is based on pv_summary. See “Configuring MC/ServiceGuard Package Dependencies” in Chapter 1 for information on configuring package dependencies.
In addition to configuring disks as MC/ServiceGuard package dependencies, you may also want to have alerts sent to a system management tool such as HP OpenView IT/Operations or Network Node Manager. Although MC/ServiceGuard and EMS work together to provide package failover, they do not send events or log the source of the failure. Also, failures may not cause a package to fail over, but may expose a single point of failure that you want to know about. Therefore, it is recommended you also configure requests from the SAM interface to EMS.
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