Extend SessionTimeout for heavy workloads

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• When you run heavy workloads in a single SMB share from Windows clients, you may encounter IO errors occasionally. The IO error is transient, IO usually succeeds after few retries.

Environment

VMware vSphere ESXi 7.0.0

Cause

• By default, if a write/read request isn't responded by the server within 60 seconds, Windows client would reset the SMB connection. For applications which doesn't retry on SMB connection reset, you would see IO errors. If applications retry on connection reset, you may not see the error at all. Most of Microsoft Office applications would retry the operation automatically in case SMB connections is reset.

Resolution

To resolve the issue:

1. Extend SessionTimeout from Windows clients. 

For example: Set-SmbClientConfiguration -SessionTimeout 120 -Force
The actual session timeout should be chosen based on the real workloads.

2. Reduce the workloads to a single share, you may create multiple shares to spread the workloads.