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What is the best MPIO policy to avoid iSCSI session interruptions during ONTAP node takeover or upgrade

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Applies to

  • ONTAP 9
  • Hyper-V Hosts using Failover Clustering
  • iSCSI

Answer

To minimize or avoid iSCSI session interruptions during ONTAP node takeover or upgrade, consider the following MPIO (Multipath Input/Output) policies:
  1. Recommended MPIO Policy: Failover Only
  • Behavior: 
    • Maintains a single primary path until a failure occurs.
    • Backup paths are only activated during a failover event.
  • Advantages: 
    • Reduces the likelihood of path re-negotiation during a takeover, ensuring session stability.
    • Ideal for environments requiring uninterrupted iSCSI sessions.
  • Use Case: 

Best suited for environments where session hiccups or interruptions are not tolerable.

  1. Alternative MPIO Policy: Low Queue Depth (LQD)
  • Behavior: 

Operates in active/active mode, distributing I/O across multiple paths with low queue depth.

  • Advantages: 

Balances load across active paths, improving performance in some scenarios.

  • Disadvantages: 

May still experience path re-negotiation during takeover or failover events, leading to brief hiccups.

  • Use Case: 

Suitable for environments where minor interruptions are acceptable and performance optimization is a priority.

  1. Avoid Using Round Robin with Subset (RRWS)
  • Behavior: 

Focuses on distributing I/O across a subset of optimal paths.

  • Disadvantages: 

More prone to session interruptions during takeover or failover events.

  • Recommendation: 

Not recommended for environments requiring high session stability.

NOTE:Before deploying the chosen MPIO policy in production, perform thorough testing in your environment to ensure it meets your stability and performance.

Additional Information

 
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.