IEA436I I/O ERROR DURING DEVICE INITIALIZATION

Explanation
During VARY,ONLINE command processing, the device
service exit received an unexpected I/O error while attempting to
obtain the physical device characteristics.
This message can
also be seen if an older device that does not support the SENSE ID
CHANNEL command is attached to an incompatible UCB type;  in other
words, the physical device does not match the logical device.

System action
The device remains offline.

Operator response
Use established procedures for reporting a
hardware error. If this appears to be a mismatch of logical and physical
device types, notify the system programmer.

System programmer response
If the logical device and physical
device are not compatible, correct the  HCD device definitions.

Source
DFSMSdfp