On excessive bit errors for the FCP channel ingress fibre path, the channel
notifies us. Previously, we only emitted a kernel message and a trace
record. Since performance can become suboptimal with I/O timeouts due to
bit errors, we now stop using an FCP device by default on channel
notification so multipath on top can timely failover to other paths. A new
module parameter zfcp.ber_stop can be used to get zfcp old behavior.
User explanation of new kernel message:
* Description:
* The FCP channel reported that its bit error threshold has been exceeded.
* These errors might result from a problem with the physical components
* of the local fibre link into the FCP channel.
* The problem might be damage or malfunction of the cable or
* cable connection between the FCP channel and
* the adjacent fabric switch port or the point-to-point peer.
* Find details about the errors in the HBA trace for the FCP device.
* The zfcp device driver closed down the FCP device
* to limit the performance impact from possible I/O command timeouts.
* User action:
* Check for problems on the local fibre link, ensure that fibre optics are
* clean and functional, and all cables are properly plugged.
* After the repair action, you can manually recover the FCP device by
* writing "0" into its "failed" sysfs attribute.
* If recovery through sysfs is not possible, set the CHPID of the device
* offline and back online on the service element.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: <stable@vger.kernel.org> #2.6.30+
Link: https://lore.kernel.org/r/20191001104949.42810-1-maier@linux.ibm.com
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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