Explanation
The channel subsystem detected a timeout condition
during the operation of device dev. 
If
the detecting component can be identified, a companion message IOS054I
may also be issued.
In the message text:
- dev
- The device number.
- chp
- The channel path identifier (CHPID), if known; otherwise, this field is set to asterisks.
- cmd
- The failing command code, if known; otherwise, this field is set to asterisks.
- stat
- The device and subchannel status, if known; otherwise, this field is set to asterisks.
- PCHID=pppp
- The physical channel id, if known.
- EXTSS=ss
- The subchannel extended status, if known.
System action
The system writes a logrec record to record this condition.
Operator response
Determine if an IOS050I message
has been issued in the same time frame for the same resource. - If an IOS050I message was issued for the same resource, then use the operator response for message IOS050I.
- If an IOS050I message was not issued, then check the resource for fabric contention using performance tools.
Source
Input/output supervisor (IOS)
Module
IOSRSLH