Extend SessionTimeout for heavy workloads on SMB share

Products

• VMware vSphere ESXi

Issue/Introduction

• When running heavy workloads in a single SMB share from Windows clients, IO errors may be encountered 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, IO errors are seen. If applications retry on connection reset, errors may not be seen at all. Most of Microsoft Office applications would retry the operation automatically in case SMB connections is reset.

Resolution

1. Extend SessionTimeout from Windows clients. 
   Set-SmbClientConfiguration -SessionTimeout 120 -Force
   The actual session timeout should be chosen based on the real workloads.
   
   
2. Avoid running heavy workloads on a single share; instead, create multiple shares to spread the workloads.