SFP power below recommended value on storage

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Category:: fas-systems

Specialty:: san

Last Updated:

Applies to

FAS/AFF systems
ONTAP 9
Fiber Channel (FC)

Issue

FC link break, link flapping and/or FCP performance degradation.
Sysconfig -a shows the status as “link not connected” or "link disconnected "
slot 0: Fibre Channel Target Host Adapter 0h (QLogic 8324 (8362) rev. 2, <LINK NOT CONNECTED>) Firmware rev: 8.9.0 Flash rev: 4.1.0 Host Port Addr: 000000 Connection: No link Switch Port: Unknown  xxxx:41 SFP Vendor Name: AVAGO SFP Vendor P/N: AFBR-57F5MZ-NA1 SFP Vendor Rev: 01 SFP Connector: LC SFP Capabilities: 4, 8, 16 Gbit/Sec
FCP-ADAPTER.XML LOG IN ASUP shows the Rx/Tx values for the affected port as 0.0 uWatts.

Rx : 0.0 (uWatts) Tx : 0.0 (uWatts)
Below error recieved regarding storage LIF on NetApp:

Service: Interface FCP XXX.FC_LIF
State: CRITICAL
Time: Wed Mar 15
15:16:13 CET 2023
Description: CRIT - State: online, 8 Gbit/s (wrong speed, expected 16 Gbit/s)(!!), Address
x0:0a:09:84:80:74:xy:xx, Read: 1235654.27, Write: 9303298.57, Read OPS: 71, Write OPS: 138, Latency: 1.15 ms, Read Latency: 0.03
ms, Write Latency: 1.08ms

Below EMS event is logged -
Tue Feb 27 00:20:29 +0000 [netapp: fct_tpd_work_thread_0: scsitarget.fct.sfpTxPowerLow:alert]: The SFP in FC target adapter 0f reports that it is transmitting (TX) at a low level of power. Operating value 263 (uWatts), Threshold value 317 (uWatts).

network fcp adapter show on ONTAP CLI displays low TX power:

Received Optical Power 570.7 (uWatts) SPF Transmitted Optical Power 123.8 (uWatts)

Low Rx power indicates an issue upstream to the storage port, i.e defective hardware incuding cable and sfp on switch end. This is not a problem with the SFP on storage.
Low Tx power indicates an issue on the storage port.
The below values are approximate values:

SFP Version	Light Value Ranges
Shortwave 2/4/8gb SFP Receive Power Range Shortwave 2/4/8gb SFP Transmit Power Range	-6 dBm (250 uWatt) to -2 dBm (630 uWatt) -6 dBm (250 uWatt) to 0 dBm (1000 uWatt)
Shortwave 4/8/16gb SFP Receive Power Range Shortwave 4/8/16gb SFP Transmit Power Range	-5.2 dBm (300 uWatt) to 0 dBm (1000 uWatt) -5.2 dBm (300 uWatt) to -1 dBm (790 uWatt)
Shortwave 8/16/32gb SFP Receive Power Range Shortwave 8/16/32gb SFP Transmit Power Range	-4.6 dBm (340 uWatt) to 2 dBm (1580 uWatt) -4.6 dBm (340 uWatt) to 2 dBm (1580 uWatt)

SFP Version

Light Value Ranges

Shortwave 2/4/8gb SFP Receive Power Range

Shortwave 2/4/8gb SFP Transmit Power Range

-6 dBm (250 uWatt) to -2 dBm (630 uWatt)

-6 dBm (250 uWatt) to 0 dBm (1000 uWatt)

Shortwave 4/8/16gb SFP Receive Power Range

Shortwave 4/8/16gb SFP Transmit Power Range

-5.2 dBm (300 uWatt) to 0 dBm (1000 uWatt)

-5.2 dBm (300 uWatt) to -1 dBm (790 uWatt)

Shortwave 8/16/32gb SFP Receive Power Range

Shortwave 8/16/32gb SFP Transmit Power Range

-4.6 dBm (340 uWatt) to 2 dBm (1580 uWatt)

May occur in correlation:
- Increasing error counters on switch ports
- IO failures and/or timeouts on host OS
- One or more failed paths from host OS
- FC Target port on storage controller is in status <OFFLINE> or <LINK NOT CONNECTED>
- Link resets/port resets
- Adapter found hung errors