Some weeks ago, VMware has discover a possible issue in all VMware vSAN 6.6 and 6.7 cluster, related to hot (or also cold) disk-extend operations.

Applications such as databases report in-guest data inconsistency on a VMDK that has been extended while residing on VMware vSAN 6.6 and later. More information of this issue are provided in the VMware KB 58715 (Virtual Machines running on VMware vSAN 6.6 and later report guest data consistency concerns following a disk extend operation).

The patch to remediate future impact, and address existing VMs which may be exposed to potential impact, has been released and is available here:

• For vSAN 6.7 – Express Patch 4 Release: http://kb.vmware.com/kb/58848
• For vSAN 6.6 – Express Patch 9 Release: http://kb.vmware.com/kb/58852

Also an alert may appear if a vSAN cluster is vulnerable to a known data consistency defect that may impact guests after a disk-extend operation:

Also the vSphere Update Manager will notify that some patches are missing, but you may not see is the vSAN cluster baseline has not been update.

Otherwise just attach the “Critical Host Patches” baseline and check the hosts compliance:

You can use the vSphere Update Manager to apply the critical host patches:

One by one you can update you ESXi hosts:

Be sure to always check the vSAN health status before procede with another host remediation and use the default maintenance mode (if you don’t want to free your host) but remember that you cannot tollerate another fault during the host reboot (if you have the standard FTT value in the VM Storage policy).

Andrea Mauro

Virtualization, Cloud and Storage Architect. Tech Field delegate. VMUG IT Co-Founder and board member. VMware VMTN Moderator and vExpert 2010-24. Dell TechCenter Rockstar 2014-15. Microsoft MVP 2014-16. Veeam Vanguard 2015-23. Nutanix NTC 2014-20. Several certifications including: VCDX-DCV, VCP-DCV/DT/Cloud, VCAP-DCA/DCD/CIA/CID/DTA/DTD, MCSA, MCSE, MCITP, CCA, NPP.