vSAN Maintenance Mode Stalled Due to Object Resync

Products

• VMware vSAN

Issue/Introduction

A vSAN host is stuck entering Maintenance Mode, and the task remains stalled at a specific percentage (e.g., 82%). The vSAN cluster shows a high amount of resyncing objects with an increasing ETA.

Symptoms

• The host entering Maintenance Mode task is stuck in the vSphere Client.
• The vSAN resyncing objects view shows a large amount of data to resync.
• The ETA for the resync operation does not decrease or is slowly increasing.

Environment

vSAN 7.x,  vSAN 8.x

Cause

The maintenance mode task is likely stalled because a vSAN object resync is taking longer than expected. This can occur when active virtual machines continue to write data to the cluster nodes while the host is attempting to enter maintenance mode, leading to stale components.

Resolution

 

1. Validate the Resync Status Check the current resync status via the vCenter Server UI under Cluster > Monitor > vSAN > Resyncing Object.

2. Check via CLI Use the following command via an SSH session on the ESXi host to verify the resync summary: esxcli vsan debug resync summary get

3. Monitor Progress If an active data transfer is identified, do not restart services on the ESXi host. Allow the resync operation to complete.

4. Best Practices

   1. Ensure the host is in maintenance mode with 'Ensure Accessibility' to prevent VM downtime.
   2. Verify that no underlying hardware faults are causing the resync to stall by checking /var/run/log/vobd.log and /var/run/log/clomd.log.