In the past, I used to occasionally go through and reclaim space on thin provisioned disks that had expanded. I was using a technique I've seen listed in lots of different places, involving running sdelete to zero out the empty space, then doing storage vmotion to migrate to a LUN with a different block size. This has worked for at least the last couple of years.
I'm trying it again today, and it's not working. When I do the storage vmotion, no space is reclaimed. I've triple-verified that I'm moving to LUNs with different block sizes. Just for testing purposes I've tried both the -z and -c option in sdelete. (My notes say -c is the way to go, but there's conflicting info out there, and the commands themselves seem to be flipped in sdelete documentation.)
The only thing that's changed is we've upgraded from version 4 to version 5 of vSphere. From what I can see, people claim it still works in v5, but that's all I've got to go on. Anybody else experiencing this.