vSAN Skyline Health --- vSAN disk group layout

Products

• VMware vSAN

Issue/Introduction

This article explains the Cluster Health- vSAN disk group layout check in the vSAN Health Service and provides details on why it might report a warning.

Environment

VMware vSAN 8.0U1 OSA and higher

Resolution

Q: What does the Cluster Health - vSAN disk group layout check do?

vSAN requires disk group layout as 64 bit to support the large capacity drive. (32bit-to-64bit conversion: With the advent of large capacity drives, vSAN required to update its internal structures to support them to allow high efficiency ratios.)

Large capacity drives are defined as capacity tier disk larger than 16TB.

The health check will validate if the disk group layout is 64 bit and if there are large capacity drives. If the disk group layout is not 64 bit, It's recommended to recreate the disk group with data evacuation. 

This health check is only applicable on capacity tier devices. It does not apply to the cache tier devices. 

Q: What does it mean when it is in a warning state?

Health check warning means the disk group contains at least one large capacity drive but the disk group layout is still 32 bit.

Check disk group layout on ESXi host with the below commands:

[root@esxi3:~] vdq -iH <--- To get the disk display name Mappings:    DiskMapping[0]:            SSD:  mpx.vmhba2:C0:T0:L0             MD:  mpx.vmhba2:C0:T1:L0 [root@#:~] vdq -s -H -d <disk display name> | grep diskgroupLayout      diskgroupLayout: 32 bit

Q: How does one troubleshoot and fix the warning state?

It's recommended to recreate the disk group with data evacuation.

There are two viable options (applicable only for ESXi 7.0 or later): 

• Recreation of disk groups with “Ensure Accessibility” option which will reduce the data redundancy
• Recreation of disk groups with “Full Data Evacuation” option which ensures Storage Policy compliance but requires sufficient storage space and may temporary require additional storage resources

Disk group recreation can be performed from Cluster - Configure - Disk management view. Select the target host and click "VIEW DISKS". Then select the target disk group for recreation. 

Once the disk group recreation is done, the health check warning should be disappeared from Skyline health UI.

Additional Information

vSAN support for large capacity drives