Windows 2012/8 and newer has improved automatic disk optimization beyond simple defrag. The Optimizer in Windows 2012/8, now takes care of maintenance activities like compacting data and compaction of file system allocation for enabling capacity reclamation on thinly provisioned disks.
You can use 3. party tools in older Windows like
http://www.raxco.com/business/products/perfectstorageI don't how this is done in Linux, sorry
Sphere 5.0 introduced the VAAI Thin Provisioning Block Space Reclamation but you have to run this manual. My guess would be that we will se this done on the fly in later versions. (Hyper-V in 2012R2 is able to do that)
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2014849