Compaq External RAID Controller & Subsystem Infortrend Operation Manual page 209

IMPORTANT!
By choosing a time value to enable the "Periodic Drive Check Time," the
controller will poll all connected drives through the controller's drive
channels at the assigned interval. Drive removal will be detected even if a
host does not attempt to access data on the drive.
If the "Periodic Drive Check Time" is set to "Disabled" (the default setting is
"Disabled"), the controller will not be able to detect any drive removal that
occurs after the controller has been powered on. The controller will only be
able to detect drive removal when a host attempts to access data on that
drive.
Advanced Configurations
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