Cluster Server 8.0 Agent for EMC SRDF/Star Configuration Guide - Windows

Last Published:
Product(s): InfoScale & Storage Foundation (8.0)
Platform: Windows

EMC SRDF/Star agent functions

The Cluster Server agent for EMC SRDF/Star (SRDFStar agent) facilitates workload site transitions.

The SRDFStar agent uses SYMCLI to do the following:

  • Verify the momentary state of the target sites and STAR (PROTECTED, CONNECTED, DISCONNECTED, HALTED, TRIPPED)

  • Switch the worlkload site from one site to the other

  • Provide a mechanism for manual interventions using action entry points

Table: Agent functions describes the agent functions:

Table: Agent functions

Function

Description

open

Checks if the lock file exists in the agent directory. The existence of the lock file indicates that a resource of type SRDFStar (the SRDFStar resource) is online.

If open detects the lock file, it waits until at least one of the resource's parent resources is probed.

It then does either of the following:

  • If the parent resource is ONLINE, the agent probably called open in response to being restarted. The agent can restart whenever it or HAD has been forcibly killed. In this case, open does not remove the lock file.

  • If the parent resource is OFFLINE, then the agent is being started in response to HAD being stopped gracefully and then restarted. In this case, open removes the lock file.

For example, if the agent calls open and detects that the lock file is present and that the disk group resource above it is ONLINE, the SRDFStar resource was probably already ONLINE. In this case, open leaves the lock file in place. If the agent detects that the disk group is OFFLINE, then the host rebooted and the application failed over, allowing no chance to delete the lock file. In this case, open removes the lock file and the agent reports OFFLINE because the group is probably ONLINE elsewhere.

online

Determines if the local site is the workload site and checks the state of Star. If the local site is the workload site and the state of Star is PROTECTED, the agent creates a lock file on the workload host. The lock file indicates that the SRDFStar resource is ONLINE and that the workload site is STAR-PROTECTED.

If the local site is the workload site but state of STAR is not PROTECTED, then the online entry point brings the workload site into STAR-PROTECTED state and creates a lock file on the workload host. If the online entry point determines that the local site is not the workload site, it tries to convert the local site to the workload site. To achieve this conversion, the online entry point tries to change the local site from either the sync or async target into the workload site. If successful, the online entry point creates the lock file on the new workload host.

monitor

Verifies that the lock file exists. If the lock file exists, the agent reports the status of the SRDFStar resource as ONLINE. If the lock file does not exist, the agent reports the status of the resource as OFFLINE.

offline

Checks the value of the HaltOnOffline attribute. If the value is 1 and the target sites are in the CONNECTED/PROTECTED state, the offline entry point issues a symstar halt command. This command halts STAR. The offline entry point also removes the lock file that is created by the online entry point.

clean

Removes the lock file that is created by the online entry point.

info

Sets the StarState attribute to the Star state as displayed in the output of the symstar query command. Reports the state of the sync and async target sites and the state of the SRDF/Star configuration. Also sends SMTP notification (if configured to do so) whenever the value of StarState changes to a different value.

action

Initiates symstar commands to perform various operations. For entry points that perform operations on specified sites, the site name is passed to the entry point as arguments.

Note:

Invoking some of the action entry points while the application is running can cause disruptions. For example, invoking the halt action while the application is running makes the underlying devices write-disabled and causes the application to crash.

The following are the action entry points:

  • connect

    Connects to a specified remote site

  • disconnect

    Disconnects from a specified remote site

  • protect

    Protects a specified remote site

  • unprotect

    Unprotects a specified remote site

  • enable

    Enables Star protection

  • disable

    Disables Star protection

  • reset

    Moves a specified site from the PATHFAIL state to the DISCONNECTED state

  • cleanup

    Performs cleanup on the specified site after a link failure

  • halt

    Brings the target sites into the HALTED state

  • halt-reset

    Brings the target sites into the DISCONNECTED state from the HALTED state

Note:

The timeout for action entry points is specified by the value of the ActionTimeout attribute. The action entry points extend this timeout value to 1 day before running the symstar commands. This behavior avoids the termination of any running symstar commands.