Hitachi Dynamic Link Manager Software Users Guide for AIX

If this happens, change any of the following settings: the checking interval
for automatic failbacks, the intermittent error-monitoring interval, or the
number of times that the error needs to occur.
If you set the number of times that the error needs to occur to 1, the above
condition does not need to be satisfied.
The following is an example of setting up automatic failback by using a
command:
# /usr/DynamicLinkManager/bin/dlnkmgr set -afb on -intvl 10
To enable the automatic failback function, set it to on. The checking interval
can be specified by the -intvl parameter. The previously specified value will
be applied when a checking interval is not specified. For example, if you turn
off the automatic failback function after the checking interval was specified as
5 minutes, and then you turn it back on (but without specifying a checking
interval) the 5 minutes that were specified from before will be used again.
Setting Up Intermittent Error Monitoring
Intermittent error monitoring is specifiable only when the automatic failback
function is enabled. To prevent an intermittent error from reducing I/O
performance, we recommend that you monitor intermittent errors when
automatic failback is enabled.
When intermittent error monitoring is enabled, you can specify intermittent
error conditions. The default value for the intermittent error-monitoring
interval is 210. The default value for the number of error occurrences is 3.
The system assumes that an intermittent error has occurred if the specified
number of times that the error needs to occur is reached during the specified
monitoring interval (minutes). A path that is assumed to have an intermittent
error is excluded from performing an automatic failback. Intermittent error
monitoring starts right when the path is recovered from the error by
performing an automatic failback. Monitoring is performed on each, individual
path.
When a value of 2 or more is specified for the number of times an error
needs to occur, make sure that the condition shown in
Setting Up the
Automatic Failback Function on page 3-80 is satisfied.
To determine whether a path is invalid for an automatic failback, you can use
the results of the dlnkmgr command's view operation.
The following is an example of setting up intermittent error monitoring by
using a command:
# /usr/DynamicLinkManager/bin/dlnkmgr set -iem on -intvl 20 -iemnum 2
on specifies that intermittent error monitoring is to be used. To disable
intermittent error monitoring, specify off. When you set this parameter to
on, you can specify intermittent error conditions by using the -intvl and -
iemnum parameters. Specify the monitoring interval for an intermittent error
in the -intvl parameter, and the number of times that the error needs to
Creating an HDLM Environment
3-81
Hitachi Dynamic Link Manager (for AIX) User Guide