DS460-12 Shelf: Persistent IOMB Loss and Multipath Errors

• DS460-12 Disk Shelf
• FAS9000 
• ONTAP 9.11.1P15
• SAS-connected shelves with IOM12B modules

• Persistent loss of communication with shelf module IOMB on DS460-12 shelf (Shelf 6), resulting in repeated “unknown link rate” alerts and “SAS disk shelf detected without a multipath configuration” errors.
• Attempts to resolve with IOMB, SAS cable, and chassis replacements did not fix the issue.
• System logs show repeated handshake errors and PCD error count increments on multiple PHYs. Shelf remained in a non-normal state with critical alerts for the IOMB module.
• SYSCONFIG -A of cluster ha can not display shelf 6 IOM B info:
  Shelf 6: DS460-12  Firmware rev. IOM12B A: 0141   B: ----

last IOM fw version is  IOM12B 0202

• STORAGE-FAULT :
  Enclosure Status: normal
Channel: 10a
Shelf: 6
Shelf Type: DS460-12
Product Serial Number: xxxx
Module Type: IOM12B
Enclosure Electronics:
Element Status                      Status Bytes  Status Descriptions
  1 [IOM12B A]    : OK                01,00,01,00   REPORT
  2: NOT INSTALLED     05,00,00,00

Enclosure:
Element Status         Status Bytes  Status Descriptions
  1: OK                01,00,02,00   FAIL

Vendor Unique Element 83-IOM12B: (SAS)
Element Status         Status Bytes  Status Descriptions
  1 [IOM12B A]    : OK                01,08,00,20   MASTER, RESERVED
  2: NOT INSTALLED     05,00,00,00

Vendor Unique Element 85-IOM12B: (ACP)
Element Status                      Status Bytes  Status Descriptions
  1 [IOM12B A]    : CRITICAL          02,18,00,40   NO ACPP, INBACP, FAIL
  2             : NOT INSTALLED     05,18,00,00

• EMS log:

[?]  Thu Sep 04 13:49:31 +0800 [node07: dsa_disc: ses.shelf.drwr.phy.rateunkwn:alert]: Drive shelf "6", module "B", drawer "1", PHY "0" is reporting an unknown link rate.
 [?]  Thu Sep 04 13:49:31 +0800 [node07: dsa_disc: ses.shelf.drwr.phy.rateunkwn:alert]: Drive shelf "6", module "B", drawer "2", PHY "0" is reporting an unknown link rate.
 [?]  Thu Sep 04 13:49:31 +0800 [node07: dsa_disc: ses.shelf.drwr.phy.rateunkwn:alert]: Drive shelf "6", module "B", drawer "3", PHY "0" is reporting an unknown link rate.
 [?]  Thu Sep 04 13:49:31 +0800 [node07: dsa_disc: ses.shelf.drwr.phy.rateunkwn:alert]: Drive shelf "6", module "B", drawer "4", PHY "0" is reporting an unknown link rate.
 [?]  Thu Sep 04 13:49:31 +0800 [node07: dsa_disc: ses.shelf.drwr.phy.rateunkwn:alert]: Drive shelf "6", module "B", drawer "5", PHY "0" is reporting an unknown link rate.
 [?]  Thu Sep 04 13:49:31 +0800 [node07: dsa_disc: ses.multipath.ReqError:alert]: SAS disk shelf detected without a multipath configuration.
 [?]  Thu Sep 04 13:49:31 +0800 [node07: dsa_disc: shelf.config.mixedha:notice]: System is using a mixture of single path, multi-path or quad-path HA storage configurations.