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Sun Cluster Data Services Developer's Guide for Solaris OS

Implementing Monitors and Methods That Execute Exclusively in the Global Zone

Most resource types execute their methods in whatever node appears in the resource group's node list. A few resource types must execute all of their methods in the global zone, even when the resource group is configured in a non-global zone, that is, either a zone-cluster node or a global-cluster non-voting node. This is necessary for resource types that manage system resources, such as network addresses or disks, which can only be managed from the global zone. These resource types are identified by setting the Global_zone property to TRUE in the resource type registration (RTR) file.

Caution – Caution –

Do not register a resource type for which the Global_zone property is set to TRUE unless the resource type comes from a known and trusted source. Resource types for which this property is set to TRUE circumvent zone isolation and present a risk.

A resource type that declares Global_zone=TRUE might also declare the Global_zone_override resource property. In this case, the value of the Global_zone_override property supersedes the value of the Global_zone property for that resource. The Global_zone_override property is described in more detail in Resource Properties and the r_properties(5) man page.

If the Global_zone resource type property is not set to TRUE, monitors and methods execute in whatever nodes are listed in the resource group's node list.

The scha_control() and scha_resource_setstatus() functions and the scha_control and scha_resource_setstatus commands operate implicitly on the node from which the function or command is run. If the Global_zone resource type property equals TRUE, these functions and commands need to be invoked differently when the resource is configured in a non-global zone.

When the resource is configured in a non-global zone, the value of the zonename operand is passed to the resource type method by the -Z option. If your method or monitor invokes one of these functions or commands without the correct handling, it incorrectly operates on the global zone. Your method or monitor should operate on the non-global zone in which the resource that is included in the resource group's node list is configured.

To ensure that your method or monitor code handles these conditions correctly, check that it does the following:

If a resource for which the Global_zone resource type property equals TRUE invokes scha_cluster_get() with the ZONE_LOCAL query optag value, it returns the name of the global zone. In this case, the calling code must concatenate the string :zonename to the local node name to obtain the zone in which the resource is actually configured. The zonename is the same zone name that is passed down to the method in the -Z zonename command-line option. If there is no -Z option in the command line, the resource group is configured in the global zone and you do not need to concatenate a zone name to the node name.

Similarly, if the calling code queries, for example, the state of a resource in the non-global zone, it must invoke scha_resource_get() with the RESOURCE_STATE_NODE optag value rather than the RESOURCE_STATE optag value. In this case, the RESOURCE_STATE optag value queries in the global zone rather than in the non-global zone in which the resource is actually configured.

The DSDL functions inherently handle the -Z zonename option. Therefore, the scds_initialize() function obtains the relevant resource and resource group properties for the non-global zone in which a resource is actually configured. Other DSDL queries operate implicitly on that node.

You can use the DSDL function scds_get_zone_name() to query the name of the zone that is passed to the method in the -Z zonename command-line option. If no -Z zonename is passed, the scds_get_zone_name() function returns NULL.

Multiple Boot methods might run simultaneously in the global zone if both of the following conditions occur: