HP Hitachi Dynamic Link Manager Software Licenses - Manual (Page 265)

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 30. 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 described in Setting Up the
Automatic Failback Function on page 3-192 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 using a command to enable intermittent error
monitoring:
# /opt/DynamicLinkManager/bin/dlnkmgr set -iem on -intvl 20 -iemnum 2
To enable intermittent error monitoring, specify on. To disable intermittent
error monitoring, specify off. When you specify on, you can use the -intvl
and -iemnum parameters to specify intermittent error conditions (the
conditions used by the system to determine whether an intermittent error is
occurring). In the -intvl parameter, specify the monitoring interval for an
intermittent error. In the -iemnum parameter, specify the number of times
that the error is to occur. When these parameters are omitted and 3 or more
errors occur within 30 minutes, the system assumes that an intermittent
error is occurring.
Setting Up Dynamic I/O Path Control
To prevent degrading of I/O performance, this function dynamically switches
the output controllers for HDLM, following the switching of controllers
performed by the storage system.
The dynamic I/O path control function can be set for each storage system or
LU. The checking interval for reviewing the switching status information can
also be set in order to properly follow the switching of controllers performed
by the storage system.
The following is an example of setting the dynamic I/O path control function:
Creating an HDLM Environment
3-193
Hitachi Dynamic Link Manager (for Linux®) User Guide