Describes the way a node uses disk shelf comparison with its partner node to determine if it is impaired.

When communication between nodes is first established through the cluster interconnect adapters, the nodes exchange a list of disk shelves that are visible on the A and B loops of each node. If, later, a system sees that the B loop disk shelf count on its partner is greater than its local A loop disk shelf count, the system concludes that it is impaired and prompts its partner to initiate a takeover.

Note: Disk shelf comparison does not function for active/active configurations using software-based disk ownership, or for fabric-attached MetroClusters.

options cf.takeover.detection.seconds number_of_seconds (But, I think this affects only cluster interconnect timeouts not the loop failure)

The valid values for number_of_seconds are 10 through 180; the default is 15.

Attention: If the specified time is less than 15 seconds, unnecessary takeovers can occur, and a core might not be generated for some system panics. Use caution when assigning a takeover time of less than 15 seconds.

On Fri, Jan 22, 2010 at 11:55 AM, Suresh Rajagopalan <SRajagopalan@williamoneil.com> wrote:

We have a active/active setup on our filers,standard loop A/loop B cabling (no multipath HA).

We had a recent event with our filers where intermittent failure of loop A did not trigger a failover to the partner. I’d like to know why that is the case. According to the Netapp failover cause and effect document at

http://now.netapp.com/NOW/knowledge/docs/ontap/rel727/html/ontap/cluster/failing_over/reference/r_oc_fo_failover-events.html

This event should have caused a failover.

The log message from the filer on loop A was:

Sun Jan 17 15:41:56 PST [netapp1: fci.link.break:error]: Link break detected on Fibre Channel adapter 0e.

Is there a option or timeout setting to make the failover happen

Thanks

Suresh

How disk shelf comparison takeover works