10.2.7. Clone Resource Agent Requirements

Any resource can be used as an anonymous clone, as it requires no additional support from the resource agent. Whether it makes sense to do so depends on your resource and its resource agent.

Globally unique clones do require some additional support in the resource agent. In particular, it must only respond with other probes for instances of the clone should result in they should return one of the other OCF error codes.

Copies of a clone are identified by appending a colon and a numerical offset, eg. apache:2.

Resource agents can find out how many copies there are by examining the OCF_RESKEY_CRM_meta_clone_max environment variable and which copy it is by examining OCF_RESKEY_CRM_meta_clone.

You should not make any assumptions (based on OCF_RESKEY_CRM_meta_clone) about which copies are active. In particular, the list of active copies will not always be an unbroken sequence, nor always start at 0.

10.2.7.1. Clone Notifications

Il supporto alle notifiche comporta che l'azione notify sia implementata. Una volta che questa è supportata all'azione notify verranno passate un numero di variabili extra che, quando combinate con le informazioni aggiuntive, potranno essere utilizzate per calcolare lo stato attuale del cluster e cosa sta per succedere ad esso.

Tabella 10.4. Variabili d'ambiente fornite alle azioni notify delle risorse clone

Variabile	Descrizione
OCF_RESKEY_CRM_meta_notify_type	Allowed values: `pre`, `post`
OCF_RESKEY_CRM_meta_notify_operation	Allowed values: `start`, `stop`
OCF_RESKEY_CRM_meta_notify_start_resource	Resources to be started
OCF_RESKEY_CRM_meta_notify_stop_resource	Resources to be stopped
OCF_RESKEY_CRM_meta_notify_active_resource	Resources that are running
OCF_RESKEY_CRM_meta_notify_inactive_resource	Resources that are not running
OCF_RESKEY_CRM_meta_notify_start_uname	Nodes on which resources will be started
OCF_RESKEY_CRM_meta_notify_stop_uname	Nodes on which resources will be stopped
OCF_RESKEY_CRM_meta_notify_active_uname	Nodes on which resources are running
OCF_RESKEY_CRM_meta_notify_inactive_uname	Nodes on which resources are not running

The variables come in pairs, such as OCF_RESKEY_CRM_meta_notify_start_resource and OCF_RESKEY_CRM_meta_notify_start_uname and should be treated as an array of whitespace separated elements.

Thus in order to indicate that clone:0 will be started on sles-1, clone:2 will be started on sles-3, and clone:3 will be started on sles-2, the cluster would set

Esempio 10.6. Esempio di variabili notifica

OCF_RESKEY_CRM_meta_notify_start_resource="clone:0 clone:2 clone:3"
OCF_RESKEY_CRM_meta_notify_start_uname="sles-1 sles-3 sles-2"