vsphere – thin provisioning
i learned something today about thin provisioning that never dawned on me before. a thinly provisioned disk clearly grows as more storage is required…but when data is deleted from the guest OS volumes the thin provisioned disk does not shrink accordingly. so if you let a 1TB thin provisioned volume grow to say 800GB then you’re stuck with a 800GB vmdk no matter how much data you delete from the guest OS. there’s forum posts and blogs regarding the use of a utility called sdelete to work around this issue, but there appears to be no easy native way to downsize a thin provisioned disk.