The failover alert delay is a configurable time period for which the waits before assessing the distribution of the storage subsystem after a logical drive ownership transfer is caused by or the multi-path driver.
If any logical drive is not on the path of its when the delay period expires, the event is logged as a critical event. A logical drive transfer alert notification is issued.
If the logical drive is transferred to the path of its preferred owner before the delay period expires, and all other logical
drives are on their preferred path, the event is not logged. An alert notification is not issued.
The logical drive transfer alert notification is issued for any instance of a logical drive owned by a non-preferred controller.
This notification occurs whether ADT is enabled and is in addition to any informational or critical event already logged within
the ADT or RDAC context.
Note:
Whenever a logical drive-not-on-preferred-path condition occurs, a Needs Attention condition is raised immediately. Only the
alert notification is delayed.
Failover Alert Delay Restrictions
These restrictions apply to the failover alert delay:
The Failover Alert Delay option operates at the storage subsystem level only.
One setting applies to all logical drives.
The default delay interval is five minutes. You can set the delay period within a range of 0 to 60 minutes. Setting the alert
delay period to 0 results in instant notification of a logical drive not on the preferred path. A value of 0 does not mean
that alert notification is disabled.
To make the best use of this feature, adjust the delay period and the failback probe interval of the host driver. Adjusting
these values makes sure that the probe runs at least once during the notification period of the failover alert delay.
Even with a correctly adjusted alert delay and failback probe time for the host driver, a logical drive ownership change might
persist through the failover alert delay period. This change also might correct itself before you inspect the situation. In
this case, a logical drive-not-on-preferred path alert is issued as a critical event, but the storage subsystem is no longer
in Needs Attention status.
Although the Failover Alert Delay option applies to RDAC, the RDAC driver is less likely to see transient “not on preferred path” conditions.
Firmware Downloads
These conditions apply to firmware downloads:
Logical drive path changes that occur as a normal part of a controller download typically do not result in a logical drive-not-on-preferred-path alert notification.
After the download has completed, the delayed logical drive distribution process is activated. The process determines whether
all of the logical drives were restored to the preferred path during the download. If any logical drives are not on their
preferred path, a critical event is logged, and an alert notification is issued.
Under ADT, a logical drive-not-on-preferred path alert might occur after a firmware download has completed. This alert occurs
if the failover driver is using the non-preferred path because of logical drive ownership changes during the firmware download.
The ADT failover driver continues to use the non-preferred path for some period of time, even though the logical drives have
been restored to their preferred owner. If the driver does not correct itself before the alert delay period expires, a critical
event is logged. To prevent such unexpected alert notifications, make sure that the alert delay period and the failback probe
interval of the multi-path driver are configured so that the probe runs at least once during the delay period.
Under RDAC, such alerts do not occur after firmware downloads. In this case, the RDAC failover driver detects logical drive
ownership changes and directs I/O down the preferred paths.