Skip to main content
NetApp Knowledge Base

High latency on FC LUN with IO WQE failure in EMS

Views:
2,882
Visibility:
Public
Votes:
2
Category:
fas-systems
Specialty:
san
Last Updated:

Applies to

  • ONTAP 9
  • FCP
  • Brocade switches
  • Cisco switches

Issue

  • Workloads on hosts accessing LUNs via FCP incur significant application and client latency
  • Frequent IO WQE failures in EMS log.

Example:

Mon Feb 10 00:28:21 +03 [NODE01: fct_tpd_work_thread_0: fcp.io.status:debug]: STIO Adapter:10a IO WQE failure, Handle 0x2, Type 8, S_ID: 20253, VPI: 18, OX_ID: 263, Status 0x3 Ext_Status 0x1d

  • Unable to access storage virtual machine data LUN on AFF SAN
  • High latency observed intermittently on FC LUN
  • Brocade switch repeatedly reported link resets due to credit loss and C3 Tx discards or timeouts on specific port under porterrshow

/fabos/cliexec/porterrshow:

          frames      enc    crc    crc    too    too    bad    enc   disc   link   loss   loss   frjt   fbsy  c3timeout    pcs    uncor

       tx     rx      in    err    g_eof  shrt   long   eof     out   c3    fail    sync   sig                  tx    rx     err    err

  0:   89.4m 139.8m   0      0      0      0      0      0      0      1.3k   0      0      0      0      0      1.3k   0      0      0  

  • Cisco switch under Fabriclog output link reset events logged for that specific port 

Switch 0; Thu Jul 28 00:00:18 2022 GMT (GMT+0:00)

00:02:11.754993 SCN LR_PORT(0);g=0x266 LR_IN                D2,P0  D2,P0  0     NA    
00:02:26.934854 SCN LR_PORT(0);g=0x266 LR_OUT               D2,P0  D2,P0  0     NA    
00:02:39.918129 SCN Port Offline;rsn=0x4,g=0x268            D2,P0  D2,P0  0     NA    
00:02:39.918135 *Removing all nodes from port               D2,P0  D2,P0  0     NA    
00:02:40.770569 SCN LR_PORT(0);g=0x268                      D2,P0  D2,P0  0     NA    
00:02:40.773044 SCN Port Online; g=0x268,isolated=0         D2,P0  D2,P1  0     NA 

  • fcp adapter stats -node <node_name> -adapter 1a -instance
    • Indicates any protocol layer issue adjacent to storage
  • network fcp adapter show on ONTAP CLI displays low TX power:

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

 

 

Sign in to view the entire content of this KB article.

New to NetApp?

Learn more about our award-winning Support

NetApp provides no representations or warranties regarding the accuracy or reliability or serviceability of any information or recommendations provided in this publication or with respect to any results that may be obtained by the use of the information or observance of any recommendations provided herein. The information in this document is distributed AS IS and the use of this information or the implementation of any recommendations or techniques herein is a customer's responsibility and depends on the customer's ability to evaluate and integrate them into the customer's operational environment. This document and the information contained herein may be used solely in connection with the NetApp products discussed in this document.