Cable attached to SAS port x is functioning in a degraded mode

Applies to

• ONTAP 9
• SAS storage shelves
• System is cabled Multipath-HA

Issue

• ONTAP Event Message System example:

[sas.cable.degraded:warning]: Cable attached to SAS port "0b" is functioning in a degraded mode

• ONTAP event log show output example:

::> event log show -event sas.cable*
Time Node      Severity Event
---- --------- -------- ---------------------------
...  node_name ERROR    sas.cable.degraded: Cable attached to SAS port "0a" is functioning in a degraded 

• ONTAP system health degraded example:

::> system health subsystem show
Subsystem         Health
----------------- ------------------
SAS-connect       degraded
Environment       ok
...
SAS-connect_Cluster ok
13 entries were displayed.

• The speed of some PHYs is reduced/disabled/rate unknown when checked from ONTAP CLI sysconfig -a output. Example:

::> system node run -node <node_name> -command sysconfig -a

slot 0: SAS Host Adapter 0a (PMC-Sierra PM8072 rev. C, SAS, <UP>)
    Firmware rev:       03.08.09.00
    Base WWN:           5:00a098:00e1428:a4
    Temperature:        Not Available
    Phy State:          [8] Enabled, 12.0 Gb/s
                        [9] Enabled, 6.0 Gb/s
                        [10] Enabled, 6.0 Gb/s
                        [11] Enabled, 12.0 Gb/s        

or

slot 0: SAS Host Adapter 0a (PMC-Sierra PM8072 rev. C, SAS, <UP>)
    Firmware rev:       03.08.09.00
    Base WWN:           5:00a098:00f46d8:30
    Temperature:        Not Available
    Phy State:          [0] Disabled
                        [1] Disabled
                        [2] Enabled, Rate unknown
                        [3] Enabled, 12.0 Gb/s

• The issue remains with a new SAS cable
• The issue remains with a new shelf IOM module, where that SAS cable is connected to.