@Miha, Thanks for the details. I consulted the defrag folks and it appears that for thinly provisioned storage, slab consolidation analysis (not the actual consolidation) is run during defrag. This unfortunately, at the moment hits the code path which checks if CSV is in redirected mode and fails defrag if it isn't. So this implies that as of now for thinly provisioned storage for defrag analysis you will need to be in redirected mode. We will work to fix this with with a future change. I will also update the blog to reflect this.
@... Repair-ClusterSharedVolume is deprecated but supported. We encourage you to use both defrag and chkdsk directly as they support CSVs. If you do intend to continue using Repair-ClusterSharedVolume note that you need to supply the Cluster Disk corresponding to the CSV. You can determine the information for the latter using the Get-ClusterSharedVolume cmdlet.
@Atul - No you don't need to put your CSV in redirected or maintenance more to run chkdsk. We will take care of restoring the state of your CSV after the chkdsk run.