After recreating a vSAN disk Group with VDI link clone environment, re-balance or recompose need to be done on vSAN before VDI logout/deploying new desktop

Products

• VMware vSAN

Issue/Introduction

In a vSAN cluster with VDI environment, when you must replace a failed cache device you delete disk groups from a host or in situation where you end up re-creating complete disk group.

When you recreate a disk group in the host after rebuild finish there are no objects in a disk group and hence the DG is empty initially.

When you logout from Linked Clone desktop the "checkpoint.vmdk"  will be removed and recreated.
If there are no objects in the disk group of the host,  checkpoint.vmdk will be deployed to the newly created disk group of the host. As all the newly created checkpoint.vmdk will be created on new diskgroup, there is possibility of heavy IO burst on the disk group once user starts log in VDI environment causing the IO congestion.

Resolution

Prevent IO burst going to single DG of vSAN that may cause by re-balance or recompose. After you create new diskgroup, you should do a proactive re-balance immediately if possible and wait till it finishes to ensure data is distributed equally across diskgroup
It is good practice to finish the proactive load -rebalance before user logs in the VDI environment. You may refer below KB article for the proactive load re-balance .

vSAN proactive rebalance

Recompose operation in VDI environment will delete all checkpoint.vmdk for all VMs and recreate all checkpoint.vmdk for all VMs. After recompose operation,  all checkpoint.vmdk are deployed to all Disk Group and checkpoint.vmdk will be distributed across all disk group evenly and IO burst will not be limited to single diskgroup