Hitachi XP P9500 User Manual page 210

When you use automatic failback, we recommend that you set
intermittent error monitoring to on to prevent an intermittent error from
reducing I/O performance.
If on is specified, be sure to also specify the intermittent error monitoring
interval and the number of times that the error is to occur. The system
assumes that an intermittent error is occurring if the specified number of
times that the error is to occur is reached during the monitoring interval.
A path that is assumed to have an intermittent error is excluded from
automatic failbacks. Intermittent error monitoring is performed on each
path. Intermittent error monitoring starts when a path is recovered from
an error by performing an automatic failback.
If you omit the intermittent error monitoring interval or the number of
times that the error is to occur, each setting is specified as follows:
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When a value of 2 or more is specified for the number of times, the
following condition must be satisfied:
error-monitoring-interval >= checking-interval-for-automatic-
failback x number-of-times-error-is-to-occur-during-intermittent-
error-monitoring
If this condition is not satisfied, the KAPL01080-W message will be output
and an error will occur. If this happens, change any of the following
settings: the checking interval for automatic failback, intermittent error
monitoring interval, or the number of times that the error is to occur.
When you set the number of times that the error is to occur to 1, the
above condition does not need to be satisfied.
The following shows the sub-parameters that should be specified: the
error monitoring interval and the number of times that the error is to
occur:
-intvl error-monitoring-interval
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When the intermittent error monitoring interval or the number of
times that the error is to occur has not been specified before:
The intermittent error monitoring interval is set to 30 minutes, and
the number of times that the error is to occur is set to 3.
When the intermittent error monitoring interval or the number of
times that the error is to occur has been specified before:
The values specified from the last time are used.
Specify the monitoring interval for an intermittent error. Use a value
from 1 to 1440 minutes. The default is 30.
During intermittent error monitoring, if changes are made to the
intermittent error monitoring interval setting or the setting for the
number of times that an error is to occur, the error count and the
elapsed time measured since monitoring has started are reset to 0.
When intermittent error monitoring is not being performed, if changes
are made in the settings of the intermittent error monitoring interval
or the number of times that an error is to occur, the new settings will
take effect after the next time an automatic failback is successful.
Because the errors and elapsed time are not counted or measured
Command Reference
Hitachi Dynamic Link Manager User Guide (for Windows(R))