Troubleshooting
Problem
The following behavior is observed when Port Protection is enabled on a network device such SAN switch. This issue is NOT related to the IBM FlashSystem A9000/R operation, host configuration or host application. This article is to help you to avoid host disconnection, when using Port Protection on a SAN switch. During the IBM FlashSystem A9000/R hot upgrade, FC ports might encounter either one or both of the following events: "Link disconnected" or "Errors on the physical layer". These events might result in host disconnection (host loss of access), if the Port Protection option on the SAN switch is enabled. These are two examples of the Port Protection options which are in use by the Cisco and Brocade switching devices. - Cisco MDS family Switch Port Guard - Brocade Network Adviser (BNA) Port Fencing If your SAN environment does not include either the Cisco or Brocade equipment, check with your vendor how to disable the Port Protection during the FlashSystem A9000/R hot upgrade. Once the FlashSystem A9000/R hot upgrade has completed, enable the Port Protection option according to the instructions, provided by the network equipment manufacturer.
Symptom
Host disconnection
Cause
During IBM FlashSystem A9000/R hot upgrade the array briefly holds IOs.
This hold causes a switch penalty, resulting in port resets with loss of synchronization and eventual host disconnection.
The root cause of the host disconnection is Port Protection functionality of the network device,which attempts to accommodate the IO burst on the SAN.
This behavior is not related to the IBM FlashSystem A9000/R operation, host configuration or host application.
Resolving The Problem
To avoid potential host disconnection, IBM recommends disabling any Port Protection on a SAN fabric switch while performing IBM FlashSystem A9000/R hot upgrade.
Consult with your network equipment vendor or customer networking team for the best operational practices.
Examples
- Refer to the following Cisco knowledge base article for details on Port Guard configuration: https://ibm.biz/BdZCeV
- Refer to the following Brocade knowledge base article for details on Port Fencing configuration: https://ibm.biz/BdZCp3
For any queries about Port Protection , contact the relevant network equipment manufacturer. For any other question about this communication, contact your IBM Technical Advisor should you have one assigned, or your IBM Representative.
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Document Information
Modified date:
17 June 2018
UID
ssg1S1012395