SFPshow on Virtual connect - want to know Rx/Tx power values

chuckk281 — Fri, 17 Oct 2014 18:55:33 GMT

Erik had an SFP tranceiver question:

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On a FC switch, the command ‘sfpshow’ displays the Rx/Tx power values. Similar command exists for HBA FC cards (the Qlogic or Emulex HBA tools).

This is a good parameter to identify if a FC cable is dirty and must be cleaned.

S-BPM14:admin> sfpshow 3/42 -f

Identifier: 3 SFP

Connector: 7 LC

Transceiver: 540c404000000000 2,4,8_Gbps M5,M6 sw Short_dist

…

low high low high

Temperature: 42 Centigrade -10 90 -5 85

Current: 7.036 mAmps 1.000 17.000 2.000 14.000

Voltage: 3290.8 mVolts 2900.0 3700.0 3000.0 3600.0

RX Power: -2.7 dBm (537.0uW) 10.0 uW 1258.9 uW 15.8 uW 1000.0 uW

TX Power: -3.3 dBm (463.6 uW) 125.9 uW 631.0 uW 158.5 uW 562.3 uW

State transitions: 3

Last poll time: 09-29-2014 CEST Mon 13:53:41

S-BPM14:admin>

Question : How to read/get this Rx/Tx power values on a virtual Connect module ? (it is not returned with the VC ‘statistics’ command).

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Reply from Lionel:

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Unfortunately not, we only provide the following transceiver information: identifier, ext-identifier, connector type, vendor-name, vendor-oui, vendor part number and vendor revision.

A few additional things are also available when you generate a support dump file but this information is only accessible to HP.

But usually a fiber cable/SFP issue generate a bunch of errors in the VCM/upstream switch statistics.

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Reply from Erik:

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Many thanks for the information.

The fact that the upstream switch had errors is very true. However, than to check remotely for a possible cause (can be HBA, SFP or cable), SAN people than check first the rx/tx power values on both sides.

This gives a very good indication if the issue/errors are due to a dirty/bad cable (most of the time it is only 1 fibre of the fibre cable which causes the issue).

95% of the cases, the issue is cable related. Than based on this stats, there is proof too in order to request datacenter people to do a particular action.

This reading of optics stats is possible to do when using HBA cards in servers, so it would be nice VCM would also displays this particular optics statistic.

Is there any method to launch this request as an feature request for a next version of VC ?

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SFPshow on Virtual connect - want to know Rx/Tx power values