Hitachi Dynamic Link Manager Software Users Guide for AIX (6.6) (T5208-96010, April 2011)

6. Command Reference
254
The previously specified interval
The explanation for the following sub-parameter describes how to specify the
checking interval.
-intvl checking-interval
Specify the checking interval between path health checks. Specify a value
from 1 to 1440 minutes depending on the user environment.
When you change the checking interval, the new setting takes effect
immediately. When the checking interval is shortened and the checking
interval after the change (from the end of the previous path health check) has
already elapsed, the path health check will start over.
The path health check interval setting remains stored in the system even if
you disable the function by changing the path health checking to
off.
Therefore, when you re-enable path health checking and do not change the
interval, the path health interval stored in the system is used.
-afb {on [-intvl checking-interval]|off}
Enables or disables automatic failback.
on: Enabled
off: Disabled
Enabling automatic failbacks might automatically place online paths online that
were intentionally placed offline (for example, paths placed offline for
maintenance work).
If you want to prevent such paths from automatically being placed online, disable
this function. When intermittent errors occur in paths or storage systems, statuses
of paths alternates between the online and offline status frequently, thus
decreasing I/O performance.
Automatic failbacks are performed on the following types of paths:
• Paths where an error occurred and for which the KAPL08022-E message
was displayed
• Path where an error occurred during the startup of the HDLM manager.
To prevent intermittent errors from deteriorating I/O performance, we
recommend that you also enable intermittent error monitoring when the automatic
failback function is enabled. Intermittent error monitoring is specifiable only
when automatic failbacks are enabled.
See Table 6-5: Relationship Between the Setting for the Automatic Failback
Function and Intermittent Error Monitoring and the Executable Operations for
the relationship between automatic failbacks and intermittent error monitoring.